Progress 10/01/01 to 06/24/04
Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? This project addresses the major byproduct - hides - of cattle that are raised domestically for their meat. Hides are the most important byproduct of the meat packing industry; about 70% of the 35 million hides that America produces annually are exported, generating over a billion dollars in foreign trade. The remainder is tanned into leather domestically, quadrupling the value of the raw material. Hides undergo several chemical and physical treatments to convert them into their primary product leather. The research contributes directly to National Program #306, "Quality, and Utilization of Agricultural Products." The project specifically contributes to Program Components "New Processes, New Uses, and Value-Added Foods and Biobased Products" and "Quality Characterization, Preservation, and
Enhancement." The replacement of sodium sulfide, an environmental pollutant and potential work hazard, as a dehairing agent in tanning requires viable alternative agents and processes. Such alternatives may include either chemically induced rapid dehairing, for application in the packing plant, or conventional time scale dehairing, enzymatic or chemical, for use in the tannery. One consequence of the implementation of rapid dehairing in the packing plant would be the ability to split raw hides and then tan just the valuable grain layer instead of the full thickness; this in turn would enable a more rapid leather manufacturing process by more efficiently using tanning chemicals and generating less waste from the hides. The slower time scale of dehairing in the tannery allows investigation of enzymatic processes that obviate using chemicals. The concentrations of natural minority constituents in a hide may affect the quality of the resulting leather. The main structural components
of the hide are two fibrous collagens. At least one of the minority constituents, the proteoglycan decorin, is intimately associated with the fibrous collagen. The development of the fibrous collagen framework in skin and other tissues is controlled by minority constituents, proteoglycans and glycoproteins, that are part protein and part carbohydrate. Although these are present in much smaller amounts than collagen, a genetic lack of some of them (e.g., decorin, the proteoglycan lumican, or the glycoprotein thrombospondin 2) during development gives rise to an abnormal collagen framework and a fragile skin. ARS researchers in a predecessor project had determined that, though much of the glycan (carbohydrate) part of the proteoglycan decorin is removed during the wet chemical processing of hides into leather, the protein part of the molecule persists, unlike other minor proteins of skin that they investigated. Researchers in the current project seek to determine the effects of the
persistence of decorin core-protein and glycan contents of the hide during processing on the physical properties of leather produced from the hide. Utilizing this information, they will determine the possible benefit of deliberately reducing the decorin core- protein and glycan (carbohydrate) content during an early stage of leather manufacture. One possible result may be a process for the controlled removal of decorin, in particular its core-protein; this has the potential benefit of yielding a softer leather. Decorin, however, is not the only minority component investigated in this manner, nor is it the only one considered by the CWU team. There is a need to establish nondestructive methods for characterizing the properties of leather, to model the drying process taking fatliquoring (application of oils and surfactants) into consideration, and to improve the UV and heat resistance of leather by the use of naturally occurring antioxidants. Currently there is no adequate method to
measure the softness of the leather after the fatliquoring process. Without a proper characterization method, the tanner has great difficulty in optimizing that process. Drying, by which leather acquires its final texture, consistency and flexibility, is one of the most important and expensive operations in leather manufacture. A mathematical model is needed that relates the factors associated with drying -- concentration of fatliquor, time, temperature, water content in the starting material -- to leather quality indicators - tensile strength, stiffness, resiliency, toughness - and to area yield. The drying model will allow the leather industry to achieve higher drying efficiency, improved quality leather, and increased area yield, thereby producing stronger leather at a reduced cost. The current commercial UV and heat protective agents such as phenols and amine derivatives are not effective for the growing market for "aniline grade" or lightly finished automotive leather. These
important inadequacies need to be studied to determine why they occur and how they may be eliminated. UV and heat can have a detrimental effect on the durability of leather, especially for instrument panels and consoles, where temperatures reach well over 100DGC. Researchers in this project are developing a finishing process using environmentally friendly antioxidants that will improve the UV- and heat resistance of automotive leather. This research will expand the demand for domestic production of high quality, durable leather, thereby contributing to the viability of the domestic tanning industry. The testing of leather at all stages of its production is an expensive and destructive process. Research in the current and predecessor projects has shown the potential for acoustic emission (AE) analysis to serve as an efficient, reliable, and nondestructive alternative. Collaboration with industry will develop AE technology into a realizable means for testing in the tannery, which in
turn will allow the optimization of the leather-making process. 2. List the milestones (indicators of progress) from your Project Plan. FY2004: CWU researchers will transfer a rapid dehairing process and/or non- sulfide oxidative dehairing technology to the tanning industry for commercial scale implementation; they will implement non-sulfide rapid dehairing in a packing plant. Bench-scale procedures will be scaled up to pilot plant-level testing. Researchers will evaluate the effect of the dual protease treatment of hides (first applied in FY02) on their sulfated glycan content, using the Alcian blue procedure developed in FY02 and FY03. They will complete studies to identify the finishing conditions that improve the UV and heat resistance of leather. The leather that ultimately results from such treatment will be tested. They will perform drying studies to formulate the relationship between water retention and the physical properties for non-chrome-tanned leather. They will also
complete the development of a portable AE tester that can be applied in- line for non-destructive measurement of leather strength and stiffness. This project is terminating. The replacement project, 1935-41440-013- 00D, has gone through the OSQR review process and has been certified. For informational purposes, the milestones for the successor project are listed: FY2005, from milestone chart for successor project 1935-41440-013-00D, 12 months: 1a, Oxidative chemical dehairing: Transfer a rapid dehairing oxidative dehairing technology to the tanning industry for commercial scale implementation; implement non-sulfide rapid dehairing in a packing plant. Conduct bench-scale experiments on a sulfide-free dehairing protocol for use in the beamhouse. 1b, Enzymatic dehairing: Apply A. tamarii protease to cattlehide dehairing at bench scale. Optimize growth conditions of A. tamarii. 1c, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating
hides with selected proteases -- Processing: Treat hides sequentially with two proteases, alkaline protease (AP) & halophile protease (HP), during an otherwise standard processing protocol. 1d, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Product evaluation: Measure decorin core-protein content by immunochemical (sandwich ELISA) procedure developed in FY2003. Correlate physical characteristics of leather product with decorin core-protein content. 2a, Drying experiments for glutaraldehyde-tanned leather: Complete studies to formulate relationship between drying conditions and physical properties of leather. 2b, Finishing process for improved UV- and heat-resistance of leather: Complete studies on the effects of UV radiation on the physical properties of leather. 2c, Nondestructive AE testing of leather properties: Complete studies to establish a mathematical model for the correlation between
AE quantities and the physical properties of leather. FY2006, from milestone chart for successor project 1935-41440-013-00D, 24 months: 1a, Oxidative chemical dehairing: Finish studies, modifying process if necessary; transfer technology. Scale up sulfide-free dehairing protocol to pilot plant-level testing. 1b, Enzymatic dehairing: Scale up enzymatic production from A. tamarii to provide material for pilot-scale trials. Run pilot-scale dehairing using A. tamarii protease. Screen commercial gelatinase to determine its potential for dehairing hides. 1c, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Processing: Treat (bate) hides with pepsin (at pH 2) as a replacement for HP, after treating (reliming) them in the presence of AP. 1d, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Product evaluation:
Test hides for their content of sulfated glycan and decorin core-protein. Test leather product for its physical characteristics. Correlate the results of the two sets of tests 2a, Drying experiments for glutaraldehyde-tanned leather: Complete studies to establish a mathematical model of the rate of drying. 2b, Finishing process for improved UV- and heat-resistance of leather: Complete studies on the effects of UV radiation on the fine structure of leather fibers. 2c, Nondestructive AE testing of leather properties: Complete the development of a portable AE tester that can be applied in-line and non- destructively measure leather strength and stiffness. FY2007, from milestone chart for successor project 1935-41440-013-00D, 36 months: 1a, Oxidative chemical dehairing: Transfer sulfide free dehairing protocol to the tanning industry. 1b, Enzymatic dehairing: Transfer A. tamarii technology to the tanning industry for commercial scale implementation. Run pilot-scale dehairing using
commercial gelatinase. Screen MMP2 (matrixmetalloproteinase-2), collagenase and heparanase. 1c, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Processing: Apply dual protease treatment to hides as above (see 12 months), but vary the duration of each treatment and the concentrations of the two proteases. 1d, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Product evaluation: Evaluate the effect of the treatments on the leather product as above (see 24 months), and thereby determine the conditions that provide the best softness and flexibility without significant adverse effect on the other physical characteristics, e.g., strength. 2a, Drying experiments for glutaraldehyde-tanned leather: Complete studies on the effects of toggling on the physical properties and dimensional stability of leather. 2b,
Finishing process for improved UV- and heat-resistance of leather: Complete studies to identify the finishing conditions that yield the best UV and heat resistance of leather. FY2008, from milestone chart for successor project 1935-41440-013-00D, 48 months: 1a. Oxidative chemical dehairing: Finish studies, modify process if necessary, and transfer technology. 1b, Enzymatic dehairing: Transfer gelatinase technology to tanning industry. Work with enzyme company to scale up successful screening work. 1c, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Processing: Treat hides with AP (during reliming) and with pepsin (as the bate) as above (cf. 24 months) during an otherwise standard processing protocol. 1d, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Product evaluation: Evaluate the effect of the
treatments on the leather product as above (see 24 months), and thereby determine the conditions that provide the best softness and flexibility without significant adverse effect on the other physical characteristics, e.g., strength. 2a, Drying experiments for glutaraldehyde-tanned leather: Complete studies that optimize the drying conditions that give the best physical properties of leather. 2b, Finishing process for improved UV- and heat-resistance of leather: Optimize parameters 2c, Nondestructive AE testing of leather properties: Complete field testing the nondestructive AE tester, and modify the tester if is necessary. FY2009, from milestone chart for successor project 1935-41440-013-00D, 60 months: 1b, Enzymatic dehairing: Transfer MMP2 collagenase or heparanase work to tanning industry. Determine most effective commercial approach for enzymatic dehairing. 1c, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with
selected proteases -- Processing: After reliming in the presence of AP, treat hides with a glycanase and then (bate) with HP or pepsin. Vary the duration and enzyme concentration during the glycanase treatment. 1d, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Product evaluation: After reliming in the presence of AP, treat hides with a glycanase and then (bate) with HP or pepsin. Vary the duration and enzyme concentration during the glycanase treatment. 2a, Drying experiments for glutaraldehyde-tanned leather: Finish studies, transfer technology. 2b, Finishing process for improved UV- and heat-resistance of leather: Finish studies, transfer technology. 2c, Nondestructive AE testing of leather properties: Finish studies, transfer technology. 3. Milestones: FY2004: CWU researchers will transfer a rapid dehairing process and/or non- sulfide oxidative dehairing technology to the tanning industry
for commercial scale implementation; they will implement non-sulfide rapid dehairing in a packing plant. Bench-scale procedures will be scaled up to pilot plant-level testing: Progress in dehairing research was reviewed with the industry at the 2004 annual meeting at ERRC of the Research Liaison Committee of the American Leather Chemists Association and with follow-up one-on-one interactions. Commercial scale implementation of rapid dehairing was delayed by the negotiating meat packing company to enable broader planning with ARS on multiple intervention strategies for cleanup of on- carcass hides (i.e., dehairing, high-pressure washing, antibacterial treatments, etc.). Industry also called for further research to determine the fate of the dehairing agents and their ability to be recycled; a procedure to monitor cyanate concentration was developed and the depletion of cyanate and peroxide was followed during recycling to determine the frequency for recharging during multiple
dehairing runs. Researchers will evaluate the effect of the dual protease treatment of hides (first applied in FY02) on their sulfated glycan content, using the Alcian blue procedure developed in FY02 and FY03: The effect of the treatment (under conditions chosen to favor the removal of decorin) on the sulfated glycan content has been observed. The experiments done will have to be replicated to ensure statistical significance. Researchers will complete studies to identify the finishing conditions that improve the UV and heat resistance of leather. The leather that ultimately results from such treatment will be tested. They will perform drying studies to formulate the relationship between water retention and the physical properties for non-chrome-tanned leather. They will also complete the development of a portable AE tester that can be applied in- line for non-destructive measurement of leather strength and stiffness: These three milestones associated with leather finishing, drying
and non- destructive testing have been substantially met. Researchers have observed that that the coating of tocopherol on the grain layer is the promising method to improve UV and heat resistance of non-chrome-tanned leather. They also have established the correlation between water content and the physical properties such as toughness and softness of leather. Under a CRADA (#58-3K95-M-978), researchers have designed a portable AE tester with a rotational AE sensor, which is applicable to in- line non-destructive testing. B. List the milestones (from the list in Question #2) that you expect to address over the next 3 years (FY 2005, 2006, & 2007). What do you expect to accomplish, year by year, over the next 3 years under each milestone? This project is terminating. The replacement project, 1935-41440-013- 00D, has gone through the OSQR review process and has been certified. For information purposes, the milestones for the successor project are listed: FY2005, from milestone
chart for successor project 1935-41440-013-00D, 12 months: 1a, Oxidative chemical dehairing: Transfer a rapid dehairing oxidative dehairing technology to the tanning industry for commercial scale implementation; implement non-sulfide rapid dehairing in a packing plant. Conduct bench-scale experiments on a sulfide-free dehairing protocol for use in the beamhouse. 1b, Enzymatic dehairing: Apply A. tamarii protease to cattlehide dehairing at bench scale. Optimize growth conditions of A. tamarii. 1c, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Processing: Treat hides sequentially with two proteases, alkaline protease (AP) & halophile protease (HP), during an otherwise standard processing protocol. 1d, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Product evaluation: Measure decorin core-protein content
by immunochemical (sandwich ELISA) procedure developed in FY2003. Correlate physical characteristics of leather product with decorin core-protein content. 2a, Drying experiments for glutaraldehyde-tanned leather: Complete studies to formulate relationship between drying conditions and physical properties of leather. 2b, Finishing process for improved UV- and heat-resistance of leather: Complete studies on the effects of UV radiation on the physical properties of leather. 2c, Nondestructive AE testing of leather properties: Complete studies to establish a mathematical model for the correlation between AE quantities and the physical properties of leather. FY2006, from milestone chart for successor project 1935-41440-013-00D, 24 months: 1a, Oxidative chemical dehairing: Finish studies, modifying process if necessary; transfer technology. Scale up sulfide-free dehairing protocol to pilot plant-level testing. 1b, Enzymatic dehairing: Scale up enzymatic production from A. tamarii to
provide material for pilot-scale trials. Run pilot-scale dehairing using A. tamarii protease. Screen commercial gelatinase to determine its potential for dehairing hides. 1c, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Processing: Treat (bate) hides with pepsin (at pH 2) as a replacement for HP, after treating (reliming) them in the presence of AP. 1d, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Product evaluation: Test hides for their content of sulfated glycan and decorin core-protein. Test leather product for its physical characteristics. Correlate the results of the two sets of tests 2a, Drying experiments for glutaraldehyde-tanned leather: Complete studies to establish a mathematical model of the rate of drying. 2b, Finishing process for improved UV- and heat-resistance of leather: Complete
studies on the effects of UV radiation on the fine structure of leather fibers. 2c, Nondestructive AE testing of leather properties: Complete the development of a portable AE tester that can be applied in-line and non- destructively measure leather strength and stiffness. FY2007, from milestone chart for successor project 1935-41440-013-00D, 36 months: 1a, Oxidative chemical dehairing: Transfer sulfide free dehairing protocol to the tanning industry. 1b, Enzymatic dehairing: Transfer A. tamarii technology to the tanning industry for commercial scale implementation. Run pilot-scale dehairing using commercial gelatinase. Screen MMP2 (matrixmetalloproteinase-2), collagenase and heparanase. 1c, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Processing: Apply dual protease treatment to hides as above (see 12 months), but vary the duration of each treatment and the concentrations of the two
proteases. 1d, Reduction or removal of decorin core protein and/or residual sulfated glycan from limed hides by treating hides with selected proteases -- Product evaluation: Evaluate the effect of the treatments on the leather product as above (see 24 months), and thereby determine the conditions that provide the best softness and flexibility without significant adverse effect on the other physical characteristics, e.g., strength. 2a, Drying experiments for glutaraldehyde-tanned leather: Complete studies on the effects of toggling on the physical properties and dimensional stability of leather. 2b, Finishing process for improved UV- and heat-resistance of leather: Complete studies to identify the finishing conditions that yield the best UV and heat resistance of leather. 4. What were the most significant accomplishments this past year? A. Single most significant accomplishment during FY 2004. Nondestructive testing of leather: Currently, the physical testing of leather is a wasteful,
destructive process, wherein cutouts are removed from the leather and sent from the tannery floor for testing. CWU researchers developed a nondestructive testing method for improving quality control, based on the processing of ultrasonic sound patterns (acoustic emission; AE). Recent tests showed that the tear strength and softness of leather can be nondestructively measured by rolling a rotational acoustic emission (AE) sensor over a leather sample. Based on the results of this investigation, CWU researchers are collaborating with industry (CRADA #58-3K95-M-978) to design an automated in-line nondestructive AE tester to be applied at the manufacturing site. Production of an in-line AE instrument will provide the industry with a nondestructive way to monitor the quality of their product at each intermediate leather-making stage. B. Other significant accomplishment(s), if any. Rapid oxidative dehairing of hides: Hair removal is one of the first steps of converting a hide into
leather. It is traditionally achieved using toxic sodium sulfide. Rapid dehairing, for use in a meat packing plant most significantly as part of a pathogen reduction program, had been developed under a CRADA in a predecessor project; it, too, used sulfide. Oxidative systems offer alternatives to the use of sulfide. During the past year, rapid oxidative dehairing was studied in detail at the lab bench scale. A procedure was developed to determine the concentration of cyanate, which in turn allowed the monitoring of the concentrations of all the ingredients in the dehairing formulation (sodium cyanate, sodium hydroxide, and hydrogen peroxide) during the dehairing reaction to determine the rate of consumption of these chemicals. Preliminary studies of waste stream remediation were initiated. The information obtained from these experiments yielded data that support the development of a CRADA with an industrial partner for extension of the bench-scale process to pilot plant and
commercial scales. Decorin analysis: Decorin, a persistent though minor constituent of hides, has eluded methodology to track its presence or disappearance during the conversion of hides into leather. Its presence or absence may contribute to leather's softness or weakness. CWU researchers proposed the use of colorimetric methods to track the decorin molecule by analyzing for its protein and carbohydrate handles. This year, they optimized a procedure they had developed in FY03 to estimate the concentrations of the protein handle, showed that the optimized method yields quantitative results, and initiated application of the method, along with a method developed in FY02 and FY03 to analyze for decorin's carbohydrate handle, to samples taken during the various stages of the processing of a hide into leather. Utilizing the two mentioned methods in such experiments will permit the researchers to determine the impact of decorin's presence or absence in the processing of hides into
leather and in the ultimate properties of that leather. Drying of chrome-free leather: The drying process is one of the key steps governing leather quality. To make quality leather, it is imperative to understand the effects of different drying methods on the physical characteristics of leather. Although CWU researchers had studied the drying of typical chrome-tanned leather in prior years, the growing demand for chrome-free leather for auto upholstery highlights the need for studying its drying. To that end, CWU researchers carried out leather drying experiments focusing on the effects of the drying method. Results showed that the method applied in a drying operation significantly affects the physical properties of leather, particularly area retention and softness. Observations indicated that toggle drying produces higher area yield; it may, however, result in stiffer leather. Vacuum drying without toggling yields better toughness and softness. The ratio of strength to stiffness
showed a strong correlation with the resultant area retention, which agrees with our previous finding for chrome-tanned leather. The information derived from this investigation will be used by leather manufacturers to select the right drying methods to meet quality demands. Protection of leather from sunlight damage: Durability of automotive leather is compromised by exposure to ultra-violet (UV) light and heat. The fast growth in the domestic production of automotive leather to meet the demands of automakers magnifies the significance of this quality. CWU researchers developed an environmentally friendly finishing process to counteract UV and heat degradation and significantly increase the UV and heat resistance of leather. The process involves application of tocopherol (Vitamin E) to the grain layer of chrome-free, glutaraldehyde- tanned leather. The treated samples were exposed to artificial sunlight at high temperature and then evaluated for the efficacy of UV and heat
resistance by testing for strength and stiffness. Leather treated with tocopherol resulted in significant improvement in strength retention and color fading resistance against UV radiation and heat. This research program will strengthen the competitiveness of the U.S. hides and leather industries by encouraging environmentally friendly production, while imparting better quality to the finished product. C. Significant activities that support special target populations. None. D. Progress Report. Dehairing of hides in the tannery: Research on oxidative systems for rapid removal of hair in a packing plant environment was conducted parallel to other research on sulfide-free protocols for use in the tannery beamhouse. Bench-scale experiments were conducted to assess the practicality of a variety of oxidative systems. Best results were seen in systems that incorporated sodium perborate or sodium percarbonate. Application of enzymes was another alternative. In a predecessor project,
enzymatic dehairing experiments were conducted using a commercially available enzyme. The dehairing conditions were optimized for that enzyme and the process time was reduced from 24 hours to 4 hours. This research was continued by a visiting scientist (Fulbright Scholar) who investigated the use of crude enzyme extracts from Bacillus subtilus for dehairing. Some of the microbiological techniques developed in that study are now being applied to the study of enzymes from A. tamarii; this work has been initiated by a visiting scientist who began his assignment on 6/30/04. Removal of hide decorin and consequences to the later processing of the hide and the characteristics of the product leather: CWU researchers anticipated that the consequences of removal of the proteoglycan decorin from hides would be the softening of leather made from those hides and enhanced 'opening-up' of the hide structure to the action of processing chemicals. They showed in FY02 that a hide treated
sequentially with two protein-digesting enzymes under conditions that were chosen to favor the removal of decorin yields, when an otherwise standard processing of the hide is completed, very soft leather. In anticipation of work to be undertaken in the successor project (1935-41440-013-00D), they showed in FY04 that the pancreatic enzyme chymotrypsin is fully active in a concentrated salt solution. Utilizing the analytical methodology developed in FY02-04 (see SC4B), the researchers obtained data suggesting that (1) treatment of a hide first with a protein-digesting enzyme active in an alkaline medium and then with a pancreatic protein-digesting enzyme in the presence of concentrated salt succeeds in removing about two- thirds of the decorin protein from the hide, (2) the treatment removes no more of the decorin carbohydrate than the much less vigorous standard processing does. Information of this kind, coupled with measurement of the physical characteristics of the leather made
from the hide, will permit the researchers to relate the decorin content of a hide treated to remove decorin to the physical characteristics, such as softness, of the leather product. In addition to its use in the above, chemical assay of the decorin-carbohydrate content of the hide also provides the capability of directly quantitating the extent of the critically important 'opening- up' of the hide structure. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. Rapid dehairing: A rapid process for removing hair from a cattle hide using concentrated sodium sulfide prior to separation of the hide from the carcass was developed in a predecessor CWU and incorporated into a commercial slaughterhouse operation as an intervention strategy for food safety. Its application reduced dirt- or manure-borne bacteria trapped on the hair that may infect the meat on the carcass; it also facilitated inspection of hide quality, significantly
decreased subsequent chemical usage by tanneries, all while maintaining the integrity of the hide for subsequent conversion into leather. Attention in the current CWU turned to finding alternatives to using sulfide as the depilatory agent, due to reasons of worker safety and effluent management. Attention focused on an oxidative system (sodium cyanate, sodium hydroxide, and hydrogen peroxide). The system was studied in detail at lab bench scale. The concentrations of the dehairing reagents were monitored during the dehairing reaction to determine the rate of consumption of these chemicals. Preliminary studies of waste stream remediation were initiated. The information obtained from these experiments yielded data that support the development of a CRADA with an industrial partner for extension of the bench-scale process to pilot plant and commercial scales (NP306, Components I and II. Milestones: Sub-Objectives 1a, 1b). Dehairing of hides in the tannery: Research on oxidative
systems for rapid removal of hair in a packing plant environment was parallel to other research on sulfide-free protocols for use in the tannery beamhouse. A number of bench-scale experiments with were conducted to assess the practicality of a variety of oxidative systems. Best results were seen in systems that incorporated sodium perborate or sodium percarbonate. Application of enzymes was another alternative. A visiting scientist (EOD 6/30/04) has initiated studies on the enzymatic dehairing of hides using a protease isolated from A. tamarii. (NP306, Components I and II. Milestones: Sub-Objectives 1b, 1c) Decorin analysis: Decorin, a persistent though minor constituent of hides, has eluded methodology to track its presence or disappearance during the conversion of hides into leather. Its presence or absence may contribute to leather's softness or weakness. CWU researchers proposed the use of colorimetric methods to track the decorin molecule quantitatively by analyzing for its
protein and carbohydrate handles. For the protein handle, they developed and optimized an immunohistochemical procedure. For decorin's carbohydrate handle, they developed a colorimetric method based on precipitation of a colored dye complex. They applied the methods to samples taken during the various stages of the processing of a hide into leather, and they altered conventional treatments of hides in the leathermaking process to allow conditions most favorable to the removal of decorin. Such removal was anticipated to lead to softer leather and enhanced 'opening-up' of the hide structure to the action of processing chemicals. The researchers showed that a hide treated sequentially with two protein-digesting enzymes under conditions that were chosen to favor the removal of decorin did indeed lead to very soft leather and a two-thirds reduction in decorin content. Utilizing the two analytical methods will permit the researchers to determine the impact of decorin's presence or
absence in the processing of hides into leather and in the ultimate properties of that leather (NP306, Components I and II. Milestones: Sub-Objectives 1d, 1e). Mechanical measurement of leather properties in the predecessor CWU: Mechanical testing procedures for leather have been in need of simplification and improved accuracy. An energy concept was applied to the characterization of the toughness of chrome-tanned bovine hides by measuring the total energy required to break the leather; toughness was observed to more accurately represent the fracture resistance of leather than tensile strength or breaking elongation. Likewise, the close relationship of toughness to greater tearing strength was shown. The researchers promoted acoustic emission (AE) testing for nondestructive measurements of the physical and mechanical properties of leather. They established a relationship between AE data and tensile strength, tear strength, brittleness, the optimal degree of opening up of leather
after liming, and the degree of lubrication (NP306, Component I. Milestones: Sub-Objective 4). Optimization of leather drying: To better understand the factors of vacuum drying leather that affect area yield and compliance, researchers in the current CWU performed systematic drying experiments to model the relationship between drying rate and drying variables (e.g., drying time, water content in the starting material, and drying temperature) using an industrial scale vacuum drying machine at the ERRC pilot tannery. The leather industry will be able to strengthen its competitiveness by determining and using the optimum drying conditions derived from this modeling, without trial-and-error. Results showed that the residual water content after drying is the key factor that governs the resultant leather properties such as dimensional stability, apparent density, and stiffness. The information obtained from this investigation will benefit the leather industry in estimating the right
drying parameters to achieve better area yield and compliance (NP306, Component I. Milestones: Sub- Objective 2e). Humectant lubricants: Traditional lubricants are known to destabilize hide (collagen) fibers and impair the mechanical strength of leather. Also, traditional fatliquors do not promote the retention of essential moisture, thus leaving the leather prone to over-drying. CWU researchers investigated the ability of low molecular weight polyethylene glycol (PEG) to solve these problems. PEG is a humectant, an agent that retains moisture, thereby preventing the leather from over-drying due to environmental changes such as low humidity and high temperature. The researchers demonstrated that treatment of leather with low molecular weight polyethylene glycol (PEG) solutions significantly reduces the stiffness of leather, indicating the strong lubrication function of PEG in leather. They also derived a mathematical model for the absorption rate of PEG. It not only reveals the
mechanism of absorption, but also predicts the absorption rate as a function of key variables. This research has provided a possible alternative or addition to traditional fatliquors, and might be used to help prevent aged leather products from becoming brittle and fragile (NP306, Component I. Milestones: Sub- Objective 2b). Maximizing area yield: Area yield is a very important issue for the leather producer because the price of a piece of leather is determined by its area. CWU researchers took an integral approach to maximizing area yield by conducting a mathematical modeling study focusing on four factors simultaneously: initial water content, fatliquor (softening oil) concentration, drying time and the number of staking passes (mechanical flexing for pliability). The resultant model gave a very systematic account of the effects of four variables and more importantly their interactions on area retention. This model will enable the tanneries to improve area yield and
consequently their profit (NP306, Component I. Milestones: Sub-Objectives 2a, 2b). Fatliquor comparison: There are many types of fatliquors (softening oils for leather) currently available in the market, but information regarding their performance in terms of physical properties is lacking. CWU researchers carried out a comparison study to determine how the physical properties were affected using a wide variety of fatliquors. Results showed that the type of fatliquor applied in a fatliquoring process does not directly affect the physical properties of leather; instead, the actual concentration of fatliquor governs the results. The information derived from this investigation will be very informative for the leather manufacturers to select the proper fatliquoring conditions to meet quality demands (NP306, Component I. Milestones: Sub-Objectives 2a, 3). Quality of chrome-free leather: The environmental and health concerns over the use and disposal of chrome-tanned leather have
encouraged the use of chrome-free leather, particularly in the European automotive leather market. The quality of chrome-free leather, particularly glutaraldehyde-tanned leather, in some respects is inferior to that of chrome-tanned leather (for example, in UV and heat resistance). For automobile applications, leather needs an environmentally friendly treatment process to counteract UV and heat degradation, and such a process must produce minimum effluents. CWU researchers applied tocopherol (Vitamin E) to the grain layer of leather. Leather coated with tocopherol showed significant improvement in strength retention and color fading resistance against UV radiation and heat. The research results may benefit the leather industry in the production of high quality, durable upholstery leather, thereby contributing to the viability of the domestic tanning industry and its markets (NP306, Component I. Milestones: Sub-Objective 3). Properties of leather surface coatings: Choosing the
right coating for leather is critical in obtaining a satisfactory finishing result, such as good flexing endurance and no surface cracking. CWU researchers proposed measuring coating properties using acoustic emission (AE) technology, which employs "listening" to and analyzing the sounds emitted by a material as it is stretched. The researchers clipped an acoustic sensor to the grain layer of finished leather in a strength test to collect various acoustic quantities, and, from the data they obtained, they established an AE method to measure the flexing endurance of leather coatings. The results of this work provide a route to measure the resultant flexibility of various coatings, which previously was difficult to measure (NP306, Component I. Milestones: Sub-Objective 3). 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the
constraints, if known, to the adoption and durability of the technology products? In general: Industry has been continually updated on progress in all areas of research in this CRIS project, particularly at the annual meetings of the American Leather Chemists Association and its research- reviewing Research Liaison Committee (which meets annually at ERRC to review the hides and leather program). Furthermore, semi-annual research updates to the rendering industry (often affiliated with the meat packing industry) were presented on the accomplishments of the entire management unit (i.e., hides & leather, fats & oils, wool, and meat & bone meal research), using the vehicle of the Emerging Issues Seminars of the Fats & Proteins Research Foundation and the National Renderers Association. Significant interactions with the private sector on a one-on-one basis have occurred, formally (CRADA's) in the areas of leather drying, acoustic emission technology, and rapid dehairing, and informally in
such areas as rapid dehairing, oxidative dehairing in the tannery, proteoglycan removal, and assessment of the integrity of leather coatings. Rapid dehairing: CRADA #58-3K95-M-913 of the predecessor CRIS project had allowed the co-development and commercialization of a sulfide-based rapid dehairing process for application in the meat packing plant. The development of a sulfide-free alternative process has led to ongoing CRADA negotiations with another packer. Meanwhile, data have been generated at the lab and pilot plant level to support such collaboration and bring it to commercial use. Cyanate analysis: In the studies carried out on the consumption of the dehairing chemicals during the cyanate/peroxide dehairing reaction, the literature techniques for the analysis of cyanate proved to be inadequate. CRIS researchers developed a new, accurate, rapid, and effective analytical technique for the cyanate determination that has the potential of being applied in the area of protein
analysis. Proteins are often denatured in concentrated urea solutions, but these solutions may contain cyanate as an impurity. The cyanate impurity interferes with the protein analysis, resulting in protein sequence errors. The new method for cyanate analysis will be of value. Decorin analysis: Methodology for detection and/or quantitation of decorin in cattle hides will be used internally. If a novel enzymatic process for the controlled removal of decorin eventually results from the data gathered using this method, that process and this methodology could be used directly by the leather manufacturers to realize softer leather and easier penetration of processing chemicals into the leather during its manufacture. The results also have implications for studies in research institutions that investigate human skin and its physiology. CRADA #58-3K95-M-1033 with a major domestic leather manufacturer, entitled "Drying Studies for Chrome-Free Leather," was established in February 2004
(C.K. Liu, ADODR) to identify the optimal drying conditions that will produce improved quality and durability of non-chrome-tanned leather. Work continued under CRADA #58-3K95-M-978 with a tannery and the manufacturer of AE equipment. The collaboration is allowing the correlation of AE testing of commercial leather with subjective and other physical methods of testing, and the initial stages in developing commercial instrumentation for in-line application of AE testing. 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. Annual meeting, Research Liaison Committee, American Leather Chemists Association ERRC, Wyndmoor, PA, April 2004. (Industry, academic, government representatives of the hides, leather and tannery supplier industries): (a) Project overview; (b) Nonsulfide Alternatives for Dehairing: Peroxide/Cyanate System for Packer Use and Perborate System for Tannery Use; (c) The Effect of Vigorous
Proteolysis on the Decorin Content of Bovine Skin: Determination of the Sulfated Glycan and Decorin Core-Protein Content of the In-Process Hide; (d) Glutaraldehyde-Tanned Leather Treated with Tocopherols; (e) Update on Leather Drying Studies; (f) Update on Nondestructive AE Testing. Semi-annual Emerging Issues & Opportunities Seminar, Fats and Proteins Research Foundation and National Renderers Association Meeting (researchers and stakeholders from rendering industry): Update on the Fats, Oils, and Animal Coproducts Research Unit (Hides and Leather Research), (a) Scottsdale, AZ, October 21, 2003; (b) Grapevine, TX, April 28, 2004.
Impacts
(N/A)
Publications
- Marmer, W.N., Dudley, R.L. 2004. The use of oxidative chemicals for the removal of hair from cattle hides in the beamhouse. Journal of American Leather Chemists Association. 99(9):386-392.
- Mozersky, S.M., Wildermuth, R.J., Marmer, W.N. 2004. Immunochemical estimation of the decorin core-protein content of preparations of bovine decorin. Journal of American Leather Chemists Association. 99(9):280-284.
- Liu, C., Latona, N.P. 2003. Application of tocopherol to improve the durability of leather. Journal of American Leather Chemists Assocation. 98(10):400-407.
- Liu, C., Latona, N.P., Lee, J. 2004. Effects of drying methods on chrome- tanned leather. Journal of American Leather Chemists Association. 99(5) :205-210.
- Liu, C., Latona, N.P. 2004. Nondestructive evaluation of leather based on acoustic emission. Journal of American Leather Chemists Association. 99(6) :251-257.
- Taylor, M.M., Liu, C., Marmer, W.N., Brown, E.M. 2003. Enzymatic modification of hydrolysis products from collagen using a microbial transglutaminase. III. preparation of films with improved mechanical properties. Journal of American Leather Chemists Assocation. 98(11):435- 444.
- Dudley, R.L., Marmer, W.N. 2004. Rapid oxidative dehairing: recycling of the dehairing reagents [abstract]. 100th Annual Meeting of the American Leather Chemists Association. Paper No. 18.
- Mozersky, S.M., Wildermuth, R.J., Marmer, W.N. 2004. Immunochemical estimation of the decorin core-protein content of preparations of bovine decorin [abstract]. 100th Annual Meeting of the American Leather Chemists Association. Paper No. 31.
- Liu, C., Latona, N.P., Lee, J. 2004. Glutaraldehyde-tanned leather treated with tocopherols [abstract]. Annual Meeting of the American Leather Chemists Association. Paper No. 13.
- Liu, C. 2004. Drying studies for glutaraldehyde-tanned leather [abstract]. 228th National Meeting of the American Chemical Society, Division of Cellulose and Renewable Materials. Paper No. 89.
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Progress 10/01/02 to 09/30/03
Outputs
1. What major problem or issue is being resolved and how are you resolving it? This project addresses the major byproduct - hides - of cattle that are raised domestically for their meat. Hides are the most important byproduct of the meat packing industry; about 70% of the 35 million hides that America produces annually are exported, generating over a billion dollars in foreign trade. The remainder is tanned into leather domestically, quadrupling the value of the raw material. Hides undergo several chemical and physical treatments to convert them into their primary product leather. The replacement of sodium sulfide, an environmental pollutant and potential work hazard, as a dehairing agent in tanning requires viable alternative agents and processes. Such alternatives may include either rapid or conventional time scale unhairing processes for the packing plant or the tannery; such processes can utilize enzymes or oxidative chemicals. One consequence of the
implementation of rapid dehairing in the packing plant would be the ability to split raw hides and then tan just the valuable grain layer instead of the full thickness. This in turn would enable a more rapid leather manufacturing process by more efficiently using tanning chemicals and generating less waste from the hides. The concentrations of natural minority constituents in a hide may affect the quality of the resulting leather. The main structural components of the hide are two fibrous collagens. At least one of the minority constituents, the proteoglycan decorin, is intimately associated with the fibrous collagen. The development of the fibrous collagen framework in skin and other tissues is controlled by minority constituents, proteoglycans and glycoproteins, that are part protein and part carbohydrate. Although these are present in much smaller amounts than collagen, a genetic lack of some of them (e.g., decorin, the proteoglycan lumican, or the glycoprotein
thrombospondin-2) during development gives rise to an abnormal collagen framework and a fragile skin. ARS researchers in a predecessor project had determined that, though much of the glycan (carbohydrate) part of the proteoglycan decorin is removed during the wet chemical processing of hides into leather, the protein part of the molecule persists, unlike other minor proteins of skin that they investigated. Researchers in the current project seek to determine the effects of the decorin core protein and glycan contents of the hide during processing on the physical properties of leather produced from the hide. Utilizing this information, they plan to determine the possible benefit of reducing the decorin core protein content of the hide, and further reducing its decorin glycan (carbohydrate) content, during an early stage of leather manufacture. There is a need to establish nondestructive methods for characterizing the softness of leather, to model the vacuum drying process taking
fatliquoring (application of oils and surfactants) into consideration, and to improve the moisture retention of leather by the use of humectants. Currently there is no adequate method to measure the softness of the leather after the fatliquoring process. Without a proper characterization method, the tanner has great difficulty in optimizing the that process. Drying, by which leather acquires its final texture, consistency and flexibility, is one of the most important and expensive operations in leather manufacture. A mathematical model is needed relating the factors associated with drying - concentration of fatliquor, time, temperature, water content in the starting material - to leather quality indicators - tensile strength, stiffness, toughness - and to area yield. Fatliquors are routinely applied to leather to lubricate the fibrous structure and to increase the compliance of leather, but at the cost of destabilizing the collagen fibers with surfactants. Traditional fatliquors
do not promote the retention of essential moisture and therefore over-drying can be the consequence. Researchers in this project are identifying new lubricants for leather that will improve moisture retention and will not require surfactants. The current commercial UV and heat protective agents such as phenol and amine derivatives are not effective for either aniline or light finished automotive leather. Moreover, these agents are potential human carcinogens and environmentally toxic. These inadequacies are of paramount importance, especially for automotive applications, and need to be studied to determine why they occur and find ways to resolve them. 2. How serious is the problem? Why does it matter? New technology that addresses leather quality and increased understanding of factors that lead to improved quality are high priority needs of the tanning industry, as expressed during annual industry reviews of this and the other hides and leather project (1935-41440-011-00D). Such
new technology and understanding will promote the survival of the tanning industry and the markets for the most valuable coproduct of the meat packing industry--animal hides. Rapid dehairing could be a component in a pathogen reduction program at a meat packing plant by mitigating bacterial contamination of the meat products during evisceration and flaying. This would benefit both the packer and the consumer. It allows early inspection for hide quality and rawhide splitting (and thus reduced processing chemicals in subsequent tanning). The use of sodium sulfide as a dehairing reagent, however, is both harmful to the environment and potentially hazardous to the workers performing this operation. The replacement of sodium sulfide would reduce both of these risks as well as reduce the amount of hazardous materials in the waste stream. How advantageous or disadvantageous decorin persistence during hide processing is to finished leather quality is as yet unknown. One possible result
of work in this project is a process for the controlled removal of decorin, in particular its core protein; this has the potential benefit of yielding a softer leather. Decorin, however, is not the only minority component investigated in this manner, nor is it the only one considered by the CWU team. With a reliable physical method such as acoustic emission (AE) to measure the softness of leather, the tanner will be able to establish an optimal fatliquoring process. A mathematical model for drying will allow the leather industry to achieve higher drying efficiency, improved quality leather, and increased area yield. The destabilization of hide (collagen) fibers and the poor moisture retention after fatliquoring and drying have been major problems for leather manufacturers. Researchers in this project are developing new lubricants to improve the moisture retention and mechanical strength of leather. This research will benefit the leather industry by producing stronger leather at a
reduced cost. There is an increasing demand from the automakers for the domestic production of automotive leather. UV and heat can have a detrimental effect on the durability of leather, especially for instrument panels and consoles, where temperatures reach well over 100DGC. Researchers in this project are developing a finishing process using environmentally friendly antioxidants that will improve the UV- and heat resistance of automobile upholstery leather. This research will benefit the leather industry in the production of high quality, durable leather, thereby contributing to the viability of the domestic tanning industry and its markets. 3. How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? This CWU addresses both components of NP #306. (I) Quality Characterization, Preservation, and Enhancement: ARS researchers aim to clarify the roles of hide composition, molecular structure, molecular interactions, and physical
state in determining the quality and functionality of the resultant leather. Also, efficient technologies and improved or new equipment will be developed for material handling that preserves quality characteristics during manufacturing steps in the conversion of hides into leather; new nondestructive technology will be developed for product grading of leather to provide rapid, accurate, and reproducible information on quality. (II) New Processes, New Uses and Value-Added Foods and Biobased Products: Research in this project will result in new uses for domestic hides; innovative new processes will be created and existing ones adapted for the manufacture of superior leather products from this agricultural commodity, with a reduction in its production costs; technology created from this research will promote an expanded, diverse range of value-added leather products from the targeted commodity. This project is closely associated with CWU 1935-41440-011- 00D (in the same MU), which
addresses biocatalytic methods for the processing of hides to leather. 4. What were the most significant accomplishments this past year? A. Single Most Significant Accomplishment during FY2003: Area yield is a very important concern for the leather producer because the price of a piece of leather is determined by its area. CWU researchers took an integral approach to maximizing area yield by conducting a mathematical modeling study focusing on four factors simultaneously: initial water content, fatliquor (softening oil) concentration, drying time and the number of staking passes (mechanical flexing for pliability). The resultant model gave a very systematic account of the effects of four variables and more importantly their interactions on area retention. This model will enable the tanneries to improve area yield and consequently their profit. B. Other Significant Accomplishment(s) if any: Most tanneries use toxic sodium sulfide to remove hair from hides. CWU researchers proposed
a sulfide-free dehairing protocol that utilizes oxidative chemicals, which are safer to handle. The researchers developed oxidative dehairing protocols for use in a tannery and a packing plant (i.e., rapid unhairing) and demonstrated that the quality of the leather obtained is not compromised. These investigations will benefit the tanning and packing industries by eliminating the use of toxic sulfide and its presence in waste effluent streams. There are many types of fatliquors (softening oils for leather) currently available in the market, but information regarding their performance in terms of physical properties is lacking. CWU researchers carried out a comparison study to determine how the physical properties were affected using a wide variety of fatliquors. Results showed that the type of fatliquor applied in a fatliquoring process does not directly affect the physical properties of leather; instead, the actual concentration of fatliquor governs the results. The information
derived from this investigation will be very informative for the leather manufacturers to select the proper fatliquoring conditions to meet quality demands. Choosing the right coating for leather is critical in obtaining a satisfactory finishing result, such as good flexing endurance and no surface cracking. CWU researchers proposed measuring coating properties using acoustic emission (AE) technology, which employs "listening" to and analyzing the sounds emitted by a material as it is stretched. The researchers clipped an acoustic sensor to the grain layer of finished leather in a strength test to collect various acoustic quantities, and from the data they obtained, they established an AE method to measure the flexing endurance of leather coatings. The results of this work provide a route to measure the resultant flexibility of various coatings, which previously was difficult to measure. For automobile applications, leather needs an environmentally friendly treatment process to
counteract UV and heat degradation, and such a process must produce minimum effluents. CWU researchers applied tocopherol (Vitamin E) and its derivatives to the grain layer of leather. Leather treated with tocopherol showed significant improvement in mechanical strength and softness and, more importantly, increased strength retention and color fading resistance against UV radiation and heat. The research results may benefit the leather industry in the production of high quality, durable upholstery leather, thereby contributing to the viability of the domestic tanning industry and its markets. Decorin, a persistent though minor constituent of hides, has eluded methodology to track its presence or disappearance during the conversion of hides into leather. CWU researchers proposed the use of colorimetric methods to track the decorin molecule by analyzing for its carbohydrate handle. This year, they developed methodology to estimate the concentrations of the protein handle.
Application of this method, along with a method developed in FY02 to analyze for decorin's carbohydrate handle, will be applied to determining the role of decorin (or its absence) in the processing of hides into leather and in the ultimate properties of that leather. C. Significant Accomplishments/Activities that Support Special Target Populations: None. D. Progress Report: Removal of hide decorin: Decorin is a seemingly persistent minor constituent in hides; its molecule is partly carbohydrate and partly protein. CWU researchers anticipated that decorin removal will lead to softening of leather made from the hides and to enhanced 'opening-up' of hide structure to the action of processing chemicals. They showed in FY02 that a hide treated sequentially with two protein-digesting enzymes under conditions that were chosen to favor the removal of decorin yields, when an otherwise standard processing of the hide is completed, a very soft leather. The analytical methodology developed in
the prior and current FY (see SC4B) will permit the researchers to relate decorin content of a hide treated to remove decorin to the physical characteristics, such as softness, of leather made from the hide. In addition to its use in the above, chemical assay of the decorin- carbohydrate content of the hide also provides the capability of directly quantitating the critically important 'opening-up' of the hide structure. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. Mechanical measurement of leather properties in the predecessor CWU: Mechanical testing procedures for leather have been in need of simplification and improved accuracy. An energy concept was applied to the characterization of the toughness of chrome-tanned bovine hides by measuring the total energy required to break the leather; toughness was observed to more accurately represent the fracture resistance of leather than tensile strength or breaking
elongation. Likewise, the close relationship of toughness to greater tearing strength was shown. The researchers promoted acoustic emission (AE) testing for nondestructive measurements of the physical and mechanical properties of leather. They established a relationship between AE data and tensile strength, tear strength, brittleness, the optimal degree of opening up of leather after liming, and the degree of lubrication. Optimization of leather drying: To better understand the factors of vacuum drying leather that affect area yield and compliance, researchers in the current CWU performed systematic drying experiments to model the relationship between drying rate and drying variables (e.g., drying time, water content in the starting material, and drying temperature) using an industrial scale vacuum drying machine at the ERRC pilot tannery. The leather industry will be able to strengthen its competitiveness by determining and using the optimum drying conditions derived from this
modeling, without trial-and-error. Results showed that the residual water content after drying is the key factor that governs the resultant leather properties such as dimensional stability, apparent density, and stiffness. The information obtained from this investigation will benefit the leather industry in estimating the right drying parameters to achieve better area yield and compliance. Humectant lubricants: Traditional lubricants are known to destabilize hide (collagen) fibers and impair the mechanical strength of leather. Also, traditional fatliquors do not promote the retention of essential moisture, thus leaving the leather prone to over-drying. CWU researchers investigated the ability of low molecular weight polyethylene glycol (PEG) to solve these problems. PEG is a humectant, an agent that retains moisture, thereby preventing the leather from over-drying due to environmental changes such as low humidity and high temperature. The researchers demonstrated that treatment
of leather with low molecular weight polyethylene glycol (PEG) solutions significantly reduces the stiffness of leather, indicating the strong lubrication function of PEG in leather. They also derived a mathematical model for the absorption rate of PEG. It not only depicts the mechanism of absorption, but also predicts the absorption rate as a function of key variables. This research has provided a possible alternative or addition to traditional fatliquors, and might be used to help prevent aged leather products from becoming brittle and fragile. Rapid dehairing: A rapid process for removing hair from a cattle hide using concentrated sodium sulfide prior to separation of the hide from the carcass was developed in a predecessor CWU and incorporated into slaughterhouse operations for reasons of food safety. Parameters were established for such processing that minimize its impact on hide quality while promoting safe and efficient recycling of the unhairing agent. That process was
incorporated into a new meat packing plant. Its application reduced dirt- or manure-borne bacteria trapped on the hair that may infect the meat on the carcass; it also facilitated inspection of hide quality, significantly decreased subsequent chemical usage by tanneries, all while maintaining the integrity of the hide for subsequent conversion into leather. Attention in the current CWU turned to finding alternatives to using sulfide as the depilitating agent, due to reasons of worker safety and effluent management. 6. What do you expect to accomplish, year by year, over the next 3 years? FY 2004: CWU researchers will transfer a rapid dehairing process and/or non- sulfide oxidative dehairing technology to the tanning industry for commercial scale implementation; they will implement non-sulfide rapid dehairing in a packing plant. Bench-scale procedures will be scaled up to pilot plant-level testing. Researchers will evaluate the effect of the dual protease treatment of hides (first
applied in FY02) on their sulfated glycan content, using the Alcian blue procedure developed in FY02 and FY03. They will complete studies to identify the finishing conditions that improve the UV and heat resistance of leather. The leather that ultimately results from such treatment will be tested. They will perform drying studies to formulate the relationship between water retention and the physical properties for non-chrome-tanned leather. They will also complete the development of a portable AE tester that can be applied in- line for non-destructive measurement of leather strength and stiffness. This project is coded to NP 306 which is currently involved in the OSQR Review Process. 7. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? CRADA #
58-3K95-M-913 (A. Gehring, ADODR) with a meat packing company, entitled "Rapid Hair Removal from Cattle Carcasses" and established in January 2002, was to establish sulfide-free procedures for the rapid dehairing of carcasses in the packing plant. Like the sulfide process developed under a prior CRADA, the new process was to have been installed and operated in a packing plant. Following the company's bankruptcy and dissolution, negotiations are underway to continue the work with another meat packer. Meanwhile, data have been generated at the lab and pilot plant level to support such collaboration and bring it to commercial use. Methodology for detection and/or quantitation of decorin in cattle hides will be used internally. If a novel enzymatic process for the controlled removal of decorin eventually results from the data gathered using this method, that process and this methodology could be used directly by the leather manufacturers to realize softer leather and easier
penetration of processing chemicals into the leather during its manufacture. The results also have implications for studies in research institutions that investigate human skin and its physiology. CRADA # 58-3K95-M-978 with a manufacturer of acoustic emission (AE) equipment and a major leather producer, entitled "Development of an On- line, Nondestructive AE Tester for the Characterization of Leather," was established in January 2003 (C.K. Liu, ADODR) to create a new method based upon the CWU's AE technology that will non-destructively and quantitatively measure leather properties. 8. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: This does not replace your peer-reviewed publications listed below). An overview of this project was presented before the U.S. Hide, Skin and Leather Association, Chicago, IL. October 2002. (representatives of the meat packing and hide trading industries) Reports on
this project were presented before the annual meeting of the Research Liaison Committee of the American Leather Chemists Association, ERRC, Wyndmoor, PA. April 2003. (industry, academic, government representatives of the hides, leather, and tannery supplier industries) Garcia, R. A. "Adding value to animal co-products," presented to Environmental Biotechnology Cooperative Research Centre, University of Queensland, Australia. July 14, 2003. Garcia, R. A. "Adding value to animal co-products," presented to technical workshop of Meat and Livestock Australia, Surfer's Paradise, Australia. July 15, 2003.
Impacts
(N/A)
Publications
- LIU, C.-K., LATONA, N.P. DIMAIO, G.L. AREA RETENTION STUDIES FOR VACUUM- DRIED LEATHER. JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION. 2002. v. 97(10). p. 381-388.
- LIU, C.-K., LATONA, N.P., DIMAIO, G.L. ACOUSTIC EMISSION STUDIES FOR LEATHER COATINGS. JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION. 2002. v. 97(10). p. 389-399.
- LIU, C.-K., LATONA, N.P. ACOUSTIC EMISSION STUDIES ON THE LUBRICATION OF A FIBROUS COLLAGEN MATERIAL-LEATHER. JOURNAL OF MATERIALS SCIENCE. 2002. v. 37(18). p. 3827-3833.
- LIU, C.-K., LATONA, N.P., DIMAIO, G.L. PHYSICAL PROPERTY STUDIES FOR LEATHER LUBRICATED WITH VARIOUS TYPES OF FATLIQUORS. JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASOCIATION. 2002. v. 97(11). p. 431-440.
- LIU, C.-K. ABSORPTION OF GLYCEROL AND ITS EFFECTS ON THE PHYSICAL PROPERTY OF A COLLAGEN MATERIAL: LEATHER. JOURNAL OF APPLIED POLYMER SCIENCE. 2003. v. 87(8). p. 1221-1231.
- GEHRING, A.G., BAILEY, D.G., DIMAIO, G.L., DUDLEY, R.L., MARMER, W.N., MAZENKO, C.E. RAPID OXIDATIVE UNHAIRING WITH ALKALINE CALCIUM PEROXIDE. JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION. 2003. v. 98(6). p. 216-223.
- MARMER, W.N., DUDLEY, R.L., DIMAIO, G.L., GEHRING, A.G. RAPID OXIDATIVE UNHAIRING WITH ALKALINE HYDROGEN PEROXIDE. JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION. 2003. v. 98(9). p. 349-356.
- GEHRING, A.G., BAILEY, D.G., CAVENG, JR. R.F., VREELAND, R.H. A RAPID METHOD FOR THE ESTIMATION OF BILE SALTS IN COMPLEX TANNING BRINES BY RPHPLC. JOURNAL OF LIQUID CHROMATOGRAPHY RELATED TECHNOLOGIES. 2003. v. 26(7). p. 1041-1050.
- GEHRING, A.G., BAILEY, D.G., CROWTHER, D.G., DIMAIO, G.L., DUDLEY, R.L., MARMER, W.N., MAZENKO, C.E. IMPROVED HIGH QUALITY AND RAPID UNHAIRING. PROCEEDINGS OF THE 27TH CONGRESS OF THE INTERNATIONAL UNION OF LEATHER TECHNOLOGISTS AND CHEMISTS SOCIETIES. 2003. p. 66-88.
- MOZERSKY, S.M., WILDERMUTH, R.J., MARMER, W.N. ESTIMATION OF THE SULFATED GLYCOSAMINOGLYCAN CONTENT OF BOVINE SKIN WITH ALCIAN BLUE. JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASOCIATION. 2003. v. 98(9). p. 335-341.
- MOZERSKY, S.M., WILDERMUTH, R.J., MARMER, W.N. ESTIMATION OF THE SULFATED GLYCOSAMINOGLYCAN CONTENT OF BOVINE SKIN WITH ALCIAN BLUE. 99TH ANNUAL MEETING OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION. 2003. Paper No. 7.
- DUDLEY, R.L., MARMER, W.N. SULFIDE FREE UNHAIRING. 99TH ANNUAL MEETING OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION. 2003. Paper No. 10.
- LIU, C.-K., LATONA, N.P. APPLICATION OF TOCOPHEROL TO IMPROVE THE DURABILITY OF LEATHER. 99TH ANNUAL MEETING OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION. 2003. Paper No. 18.
- LIU, C.-K., LATONA, N.P. PHYSICAL PROPERTY STUDIES FOR A COLLAGEN MATERIAL: LEATHER TREATED WITH TOCOPHEROL. 226TH NATIONAL MEETING OF THE AMERICAN CHEMICAL SOCIETY. 2003. Paper No. PMSE154.
- Marmer, W.N., Solaiman, D., Foglia, T.A., Brown, E.M. 2003. Non-food utilization of animal coproducts [abstract]. American Chemical Society. Paper No. AGFD104.
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Progress 10/01/01 to 09/30/02
Outputs
1. What major problem or issue is being resolved and how are you resolving it? This project addresses the major byproduct -hides-of cattle that are raised domestically for their meat. Hides are the most important byproduct of the meat packing industry; about 60% of the 35M hides that America produces annually are exported, generating over a billion dollars in foreign trade. The remainder is tanned into leather domestically, quadrupling the value of the raw material. Hides undergo several chemical and physical treatments to convert them into their primary product leather. The replacement of sodium sulfide, an environmental pollutant and potential work hazard, as an unhairing agent in tanning requires viable alternative agents and processes. Such alternatives may include either rapid or conventional time scale unhairing processes for the packing plant or the tannery; such processes can utilize enzymes or oxidative chemicals. One consequence of the implementation of
rapid unhairing in the packing plant would be the ability to split raw hides and then tan just the valuable grain layer instead of the full thickness. This in turn would enable a more rapid leather manufacturing process by more efficiently using tanning chemicals and generating less waste from the hides. The concentrations of natural minority constituents in a hide may affect the quality of the resulting leather. The main structural components of the hide are two fibrous collagens. At least one of the minority constituents, the proteoglycan decorin, is intimately associated with the fibrous collagen. The development of the fibrous collagen framework in skin and other tissues is controlled by minority constituents, proteoglycans and glycoproteins, that are part protein and part carbohydrate. Although these are present in much smaller amounts than collagen, a genetic lack of some of them (e.g., decorin, the proteoglycan lumican, or the glycoprotein thrombospondin 2) during
development gives rise to an abnormal collagen framework and a fragile skin. ARS researchers in a predecessor project had determined that, though much of the glycan (carbohydrate) part of the proteoglycan decorin is removed during the wet chemical processing of hides into leather, the protein part of the molecule persists, unlike other minor proteins of skin that they investigated. Researchers in the current project seek to determine the effects of the decorin core protein and glycan contents of the hide during processing on the hide's physical properties and those of leather produced from it. They also plan to determine the possible benefit of reducing the decorin core protein content of the hide, and further reducing its decorin glycan (carbohydrate) content, during an early stage of leather manufacture. There is a need to establish nondestructive methods for characterizing the softness of leather, to model the vacuum drying process taking fatliquoring (application of oils and
surfactants) into consideration, and to improve the moisture retention of leather by the use of humectants. Currently there is no adequate method to measure the softness of the leather after the fatliquoring process. Without a proper characterization method, the tanner has great difficulty in optimizing the that process. Drying, by which leather acquires its final texture, consistency and flexibility, is one of the most important and expensive operations in leather manufacture. A mathematical model is needed relating the factors associated with drying - concentration of fatliquor, time, temperature, water content in the starting material - to leather quality indicators - tensile strength, stiffness, toughness - and to area yield. Fatliquors are routinely applied to leather to lubricate the fibrous structure and to increase the compliance of leather, but at the cost of destabilizing the collagen fibers with surfactants. Traditional fatliquors do not promote the retention of
essential moisture and therefore over-drying can be the consequence. Researchers in this project are identifying new lubricants for leather that will improve moisture retention and will not require surfactants. 2. How serious is the problem? Why does it matter? New technology that addresses leather quality and increased understanding of factors that lead to improved quality are high priority needs of the tanning industry, as expressed during annual industry reviews of this and the other hides and leather project (1935-41440-011-00D). Such new technology and understanding will promote the survival of the tanning industry and the markets for the most valuable coproduct of the meat packing industry--animal hides. Rapid unhairing could be a component in a pathogen reduction program at a meat packing plant by mitigating bacterial contamination of the meat products during evisceration and flaying. This would benefit both the packer and the consumer. It also allows early inspection for
hide quality and rawhide splitting (and thus reduced processing chemicals in subsequent tanning). The use of sodium sulfide as an unhairing reagent, however, is both harmful to the environment and potentially hazardous to the workers performing this operation. The replacement of sodium sulfide would reduce both of these risks as well as reduce the amount of hazardous materials in the waste stream. How advantageous or disadvantageous decorin persistence during hide processing is to finished leather quality is as yet unknown. One possible result of work in this project is a process for the controlled removal of decorin, in particular its core protein; this has the potential benefit of yielding a softer leather. Decorin, however, is not the only minority component investigated in this manner, nor is it the only one considered by the CWU team. With a reliable physical method such as acoustic emission (AE) to measure the softness of leather, the tanner will be able to establish an
optimal faliquoring process. A mathematical model for drying will allow the leather industry to achieve higher drying efficiency, improved quality leather, and increased area yield. The destabilization of hide (collagen) fibers and the poor moisture retention after fatliquoring and drying have been major problems for leather manufacturers. Researchers in this project are developing new lubricants to improve the moisture retention and mechanical strength of leather. This research will benefit the leather industry by producing stronger leather at a reduced cost. 3. How does it relate to the national Program(s) and National Program Component(s) to which it has been assigned? This CWU addresses both components of NP #306. (A) Quality Characterization, Preservation, and Enhancement: ARS researchers aim to clarify the roles of hide composition, molecular structure, molecular interactions, and physical state in determining the quality and functionality of the resultant leather. Also,
efficient technologies and improved or new equipment will be developed for material handling that preserves quality characteristics during manufacturing steps in the conversion of hides into leather; new nondestructive technology will be developed for product grading of leather to provide rapid, accurate, and reproducible information on quality. (B) New Processes, New Uses, and Value-Added Biobased Products: Research in this project will result in new uses of domestic hides; innovative new processes will be created and existing ones adapted for the manufacture of superior leather products from this agricultural commodity, with a reduction in its production costs; technology created from this research will promote an expanded, diverse range of value-added leather products from the targeted commodity. This project is closely associated with CWU 1935-41440-011-0D (in the same MU), which addresses biocatalytic methods for the processing of hides to leather. 4. What was your most
significant accomplishment this past year? A. Single Most Significant Accomplishment during FY 2002 year: Traditional lubricants are known to destabilize hide (collagen) fibers and impair the mechanical strength of leather. Also, traditional fatliquors do not promote the retention of essential moisture, thus leaving the leather prone to over-drying. The use of low molecular weight polyethylene glycol (PEG) may solve these problems. PEG is a humectant with the ability to retain moisture, thereby preventing the leather from over-drying due to environmental changes, such as low humidity and high temperature. CWU researchers demonstrated this year that leather treated with low molecular weight polyethylene glycol (PEG) solutions significantly reduces the stiffness of leather, indicating the strong lubrication function of PEG in leather. They also derived a mathematical model for the absorption rate of PEG. It not only depicts the mechanism of absorption, but also predicts the
absorption rate as a function of key variables. This research may provide a possible alternative or supplement to traditional fatliquors and thereby help prevent aged leather products from becoming brittle and fragile. B. Other Significant Accomplishment(s) if any: Only toxic sodium sulfide has been used in the rapid unhairing of animal carcasses in the meat packing plant environment. CWU researchers this year developed a rapid unhairing protocol that utilizes oxidative chemicals, which are safer to handle. The quality of the leather obtained from the oxidative unhairing protocol is similar to leather made from hides that had undergone unhairing by sulfide. This investigation will benefit the meat packing industry as the unhairing protocol could be utilized in a packing plant to produce hides that are free of hair (and attached manure and dirt); hair-free hides, in turn, allow quality inspection and early-stage hide splitting (which has the potential for savings in the amount of
processing chemicals and processing time downstream in the tanneries). Information is lacking regarding the effect of the concentration of fatliquor (softening oils) on the vacuum drying of leather. CWU researchers derived a mathematical equation to precisely describe the relationship between the fatliquor concentration and drying rate as well the resultant leather's physical properties. The equation benefits the leather industry in estimating the right drying parameters to dry leather without trial and error. Two processes are used in tanneries to soften leather. One is staking, a mechanical flexing for pliability, and the other is the application of fatliquors (softening oils). There has been little understanding of how one process affects the other. CWU researchers studied the effects of staking on the properties of vacuum-dried leather and the interaction between staking and fatliquoring. They discovered an intricate effect of fatliquor on the softening behavior of staking.
Without fatliquor, staking actually stiffens the leather. Data showed that the softening action of staking only becomes effective after the fatliquor concentration reaches a certain level. This information gives important guidance to the leather industry in their preparation of a quality product. C. Significant Accomplishments/Activities that Support Special Target Populations: None. D. Progress Report: Removal of minority constituent decorin in hides: Under the predecessor CWU 1935-41440-007-00D, ERRC researchers investigated the treatment of hides with either one of two enzymes that digest proteins under widely different conditions; one enzyme works in an alkaline medium, which is known to favor the removal of the glycan (carbohydrate) part of decorin, whereas the other enzyme works in a high salt environment, which is presumed to loosen the attachment of the decorin core protein from the major hide component, collagen. Now, researchers under the present CWU have examined the
effect of treating a hide with these two enzymes sequentially. The sequential treatment appeared to somewhat adversely affect the quality of leather produced from the treated hide, but not so much as to interfere with sampling of the hide to determine its decorin glycan and protein contents. An additional impact of this work is that the determination of the glycan content provides the capability of directly and precisely quantitating, by chemical assay, the critically important 'opening-up' of hide structure to the action of processing chemicals. 5. Describe your major accomplishments over the life of the project, including their predicted or actual impact? Mechanical measurement of leather properties: Under the predecessor CWU 1935-41440-007-00D, an energy concept was applied to the characterization of the toughness of chrome-tanned bovine hides by measuring the total energy required to break the leather. This physical quantity (toughness) was observed to more accurately represent
the fracture resistance of leather than tensile strength or breaking elongation. Results from that work also demonstrated the importance of toughness to leather quality, its close relationship to greater tearing strength, and how to improve the toughness of leather. The leather industry will benefit from using these energy methods to accurately characterize toughness and to understand how processing factors affect the toughness of their leather products. Consequently, the results of this investigation will lead tanneries to the optimization of the leather making process, yielding higher quality leather products. Mechanical measurement of leather properties: Researchers in the predecessor CWU also clarified the difference between the tearing and tensile behavior and their fracture mechanisms. Observations showed that the tearing strength did not correlate well to the tensile strength. Instead, they discovered that the tearing strength is directly related to leather's toughness,
i.e., the tougher the leather, the better the tearing strength. The information derived from this investigation gives tanneries a better understanding of the importance of toughness to leather quality and its close relationship to stronger tearing strength, thereby leading them to the optimization of the leather making process and higher quality leather. Mechanical measurement of leather properties: Under the predecessor CWU, researchers established a relationship between acoustic emission (AE) data and tensile strength. Observations also showed good correlation between AE data and tear strength; higher acoustic counts indicate a brittle leather structure, resulting in poor tear strength. The results from those studies will lead to production of a commercially usable AE tester under the current CWU, thus providing the leather industry with a nondestructive way to monitor the strength of leather at each intermediate leather-making stage without damaging the leather. Mechanical
measurement of leather properties: Prior to accomplishments under the predecessor CWU, there was no reliable method to measure the degree of opening up and lubrication for partially processed leather. ARS researchers established ultrasonic methods (acoustic emission; AE) for quantifying the degree of opening up and lubrication of hides and leather. Observations showed that AE count measurements can determine the optimal degree of opening up of leather after liming. Research results also indicated that a lower acoustic hit count indicates a higher degree of lubrication. The leather industry will be able to apply AE methods to determine the proper liming and fatliquoring conditions to produce high quality leather products. Mechanical measurement of leather properties: To better understand the factors of vacuum drying leather that affect area yield and compliance, researchers in the current CWU performed systematic drying experiments to model the relationship between drying rate and
drying variables (e.g., drying time, water content in the starting material, and drying temperature) using an industrial scale vacuum drying machine at the ERRC pilot tannery. The leather industry will be able to strengthen its competitiveness by determining and using the optimum drying conditions derived from this modeling, without trial-and-error. Results showed that the residual water content after drying is the key factor that governs the resultant leather properties such as dimensional stability, apparent density, and stiffness. The information obtained from this investigation will benefit the leather industry in estimating the right drying parameters to achieve better area yield and compliance. 6. What do you expect to accomplish, year by year, over the next 3 years? FY 2003: CWU researchers will scale-up bench-scale unhairing procedures to pilot plant-level testing. They will conduct bench-scale experiments on non-sulfide unhairing with enzymes. They will evaluate the
effect of the dual protease treatment (section D above) and of treatment with selected carbohydrate-digesting enzymes, viz., xylosidases and/or glucuronidases, on the decorin core protein and glycan ( carbohydrate) contents of the treated hides. They will perform drying experiments for non-chrome tanned leather to establish a mathematical model describing the relationship between water retention and drying variables. They will begin the development of a portable AE tester that can be applied on-line to nondestructively measure the softness and strength of leather. FY 2004: CWU researchers will transfer a rapid unhairing process and/or non-sulfide oxidative unhairing technology to the tanning industry for commercial scale implementation; they will implement non-sulfide rapid unhairing in a packing plant. Bench-scale procedures will be scaled up to pilot plant-level testing. Researchers will evaluate treating hides with the protein-digesting enzyme pepsin (at pH 2) (Deselnicu,
1994) as a replacement for the halophile enzyme preparation of earlier experiments (section D above), after reliming in the presence of alkaline protease. The leather that ultimately results from such treatment will be tested. They will complete studies to identify the finishing conditions that improve the UV and heat resistance of leather. The leather that ultimately results from such treatment will be tested. They will perform drying studies to formulate the relationship between water retention and the physical properties for non-chrome-tanned leather. FY2005: CWU researchers will transfer a non-sulfide enzymatic unhairing process to the tanning industry for commercial scale implementation. They will have an antibody made commercially against a specified region of the decorin molecule at a substantial distance from the amino end of the molecule, against which the presently used antibody is directed the new antibody will be used to determine whether all or only part of the decorin
core protein survives the chemical treatment to which the hide is subjected during processing. Based on previous research information along with SAS statistical analysis, researchers will identify the optimum drying and lubrication conditions to produce the best physical properties for non-chrome-tanned leather. Experiments will be conducted to verify those optimum conditions. The researchers will also complete field-testing of the non-destructive AE tester, and modify the tester if necessary. Successfully developed AE technology will be transferred to industry. 7. What technologies have been transferred and to whom? When is the technology likely to become available to the end user (industry, farmer other scientist)? What are the constraints, if known, to the adoption durability of the technology? Nondestructive testing of leather: CWU researchers successfully used a unique acoustic emission (AE) sensor to nondestructively measure the softness of milled and crust leathers.
Optimal testing conditions were identified. The researchers discovered the AE cumulative count is the most sensitive AE quantity to correlate to softness of leather. The results have attracted private sector interest in a collaboration with ERRC. A potential collaborator is preparing an SBIR grant proposal to fund the development of a commercial scale nondestructive AE tester for application in tanneries. 8. List your most important publications and presentations, and articles written about your work (NOTE: this does not replace your review publications which are listed below) Reports on all hides and leather phases of this project were presented to the annual meeting of the Research Liaison Committee of the American Leather Chemists Association, ERRC, Wyndmoor, PA. 2002. (industry, academic, government representatives of the hides, leather, and tannery supplier industries). Press release: Core, J. New tanning process good for industry and the environment. ARS. 2001.
(http://www.ars.usda.gov/is/pr/2001/010815.htm)
Impacts
(N/A)
Publications
- Liu, C.-K. Marmer, W.N. USDA's research on the physical properties of leather. China Leather. 2001. v. 30(17). p. 30-33.
- Liu, C.-K., Latona, N.P., DiMaio, G.L. Effects of fatliquor on vacuum drying of leather. Journal of the American Leather Chemists Association. 2002. v. 97(7). p. 284-293.
- Taylor, M.M., Liu, C.-K., Latona, N.P., Marmer. W.N., Brown, E. Enzymatic modification of hydrolysis products from collagen using a microbial transglutaminase. II. Preparation of films. Journal of the American Leather Chemists Association. 2002. v. 97(6). p. 225-234.
- Liu, C.-K., Latona, N.P., DiMaio, G.L. Lubrication of leather with polyethylene glycol. Journal of the American Leather Chemists Association. 2002. v. 97(9). p. 351-363.
- Dudley, R.L., Gehring, A.G., Marmer, W.N. Rapid oxidative unhairing using hydrogen peroxide. American Leather Chemists Association. 2002. Abstract p. 29.
- Liu, C.-K., Latona, N.P., DiMaio, G. Lubrication of leather with polyethylene glycol. American Leather Chemists Association. 2002. Abstract p. 21.
- Liu, C.-K., Latona, N.P., DiMaio, G. Absorption and acoustic emission studies for a collagen material - leather treated with polyethylene glycol. American Chemical Society. 2002. Abstract PMSE 271.
- Gehring, A.G., Bailey, D.G., DiMaio, G., Crowther, J. Improved hide quality and rapid unhairing. Journal of the American Leather Chemists Association. 2002. v. 97(9). p. 339-348.
- Mozersky, S.M., Iandola, S.K., Marmer, W.N. Leather made from the hides of double-muscled cattle has satisfactory physical characteristics. Journal of the American Leather Chemists Association. 2001. v. 96(10). p. 393-397.
- Mozersky, S.M., Allen, O.D., Marmer, W.N. Vigorous proteolysis: reliming in the presence of an alkaline protease and bating (post-liming) with an extremophile protease. Journal of the American Leather Chemists Association. 2002. v. 97(4). p. 150-155.
- Liu, C.-K., DiMaio, G.L. Effects of vacuum drying variables on the mechanical properties of leather. Journal of the American Leather Chemists Association. 2001. v. 96(7). p. 243-254.
- Liu, C.-K., Latona, N.P., DiMaio, G.L. Degree of opening up of the leather structure characterization by acoustic emission. Journal of the American Leather Chemists Association. 2001. v. 96(10). p. 367-381.
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