Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: For skins: Fish skins are one of the by-products from the fish processing industry that is usually processed into fish meal. Recent studies showed that fish skin might successfully be used for gelatin production. There are a number of processing parameters affecting gelatin's quality and usefulness. This study is designed to optimize processing parameters to get the highest yield, gel strength, and viscosity for gelatin from silver carp skin. For these experiments, 9 processing parameters were selected as independent variables and the three parameters above as dependent variables. The independent parameters were concentrations of acid and alkali used in the pretreatment step, the durations and temperatures of the acid and alkali steps, the extraction temperature and duration, and finally the water/skin ratio. A fractional factorial design (2 levels, resolution III, 29-5) was chosen for this study. At the end of the extractions, the protein yield varied between 4.5 and 20.3%. Hydroxyproline (Hyp) content of silver carp skin gelatin was 19.5% for the sample giving the highest Hyp/protein ratio suggesting that it was the purest gelatin extracted. If this sample is arbitrarily accepted as pure gelatin, the purity of the remaining 15 samples would be between 68.9 and 92.8%. The protein content of skin was found to be 26.0% using a Kjeldahl factor of 5.4. Thus, the highest protein and gelatin recovery obtained was 78.1 and 98.8% of the total available, respectively. The Hyp content and Hyp/protein ratio of the skin were found to be 3.4 and 13.0%, respectively. These data suggest that the protein of the skin is not completely collagen and about 33.5% of skin protein is composed of non-collagen protein and/or nitrogen containing non-protein substances. Furthermore, the data indicate that the Hyp content of gelatin extracted from silver carp skin by the Woessner method is higher than what has been reported using the Woessner method for gelatins obtained from skins of other fish species. Further work on optimization of extraction conditions and characterization of the gelatin is planned. For scales: Pretreatments with different chemicals at different concentrations were used to determine their effects on gelatin extraction from silver carp (Hypophthalmichthys molitrix) scales. During calcium removal with HCl, citric acid, and EDTA, all three chemicals had a high decalcification rate (＞90%), however, protein losses with EDTA were lower than with HCl and citric acid, and protein losses with citric acid were lower than with HCl. The gelatin extracted after 0.20 mol/L HCl for calcium removal (92% decalcification rate) gave a yield of 17.2% and a gel strength of 128 g, and gelatin extraction after 10 and 12% citric acid for calcium removal (91 and 92% decalcification rates, respectively) gave a yield of 10.3% and a gel strength of 97 g, while that following 0.20 mol/L EDTA (92% decalcification rate) had a yield of 22% and a high gel strength of 152 g. These data suggest that EDTA at 0.20 mol/L provides the best Ca removal with minimal collagen/gelatin removal during the Ca removal step, giving a high gelatin yield and gel strength. PARTICIPANTS: Joe M. Regenstein: Principle Investigator Yifen Wang: Collaborator, Auburn University Yan Wang: Visiting Scientist from China Gokhan Boran: Ph.D. Student from Turkey Wiparwee Sakaorattanakul: Masters of Professional Studies from Thailand Yosuke Yasumuro: Master of Professional Studies from Japan James Schafer: Schafer Fisheries - Providing materials Motty Berger: A&B Gefilte Fish - Providing materials TARGET AUDIENCES: The main beneficiary of this work will be the fishing industry that generates the wastes that can now be converted into much higher value products. However, the work is also targeted at the food industry that is looking to expand their offerings of kosher and halal products. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The goal of this work is to provide information that will be helpful in developing value added products that the fishing industry can use to encourage greater use of the carcass once harvested. This makes good sense both economically and in terms of sustainability. Gelatin is one of the most widely used food ingredients; its usage is measured in tons not pounds. Besides providing additional income to the seafood industry, this product would fill some unique marketing opportunities, i.e., it can be produced so that it can meet Jewish kosher standards and Muslim halal standards. Although it has been shown to not transmit the prions for Bovine Spongioform Encephalopathy (mistakenly called Mad Cow Disease), there are still niches that want to move away from warm blooded animal gelatins. Hopefully, this work will provide technical guidelines for the expansion of this slowly emerging industry.
Publications
- Wang, Y. and Regenstein, J.M. 2008. Effect of EDTA, HCl, and Citric Acid on Calcium Salt Removal from Asia Carp Scales Prior to Gelatin Extraction. Abstract booklet: Atlantic Fisheries Technological Conference, Oct. 19-22, Wilmington, NC.
- Boran, G. and Regenstein, J.M. 2008. Optimization of Gelatin Extraction from Silver Carp Skin. Abstract booklet: Atlantic Fisheries Technological Conference, Oct. 19-22, 2008, Wilmington, NC.
- Wang, Y. Yang, H, and Regenstein, J.M. 2008. Abstract booklet: Effect of Different Pretreatments on Nanostructure and Physical Properties of Catfish Skin Gelatin. Atlantic Fisheries Technological Conference, Oct. 19-22, 2008, Wilmington, NC.
- Regenstein, J.M. 2008. Animal Welfare Concerns for Fish. Abstract booklet: Atlantic Fisheries Technological Conference, Oct. 19-22, 2008, Wilmington, NC.
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: The properties and development of fish gelatins continues to be investigated. Current efforts have involved providing advice to a group in Alabama working on catfish gelatin.
PARTICIPANTS: The current work is being done in conjunction with Auburn University, Alabama A&M University and Tuskeegee University.
TARGET AUDIENCES: The project is based on providing the fish processing industry with a higher value product from the fish skin waste from filleting. The users would be companies using gelatin trying to make a more widely accepted and possibly better product. A key benefit of fish gelatins is their range of melting points. Another benefit is that it has no association with potential concerns such as BSE. Some fish gelatins can also be prepared as kosher and/or halal in keeping with the Jewish and Muslim dietary laws, respectively, at a lower cost than those currently available to the normative mainstream, especially on the kosher side. Most currently kosher certified gelatins are not accepted by the normative mainstream. Catfish gelatin it should be noted is halal acceptable but is not kosher.
Impacts
An increased understanding of the best ways to produce fish gelatins and how to use them continues to be the focus of the current work.
Publications
- Yang, H., Wang, Y. and Regenstein, J.M. 2007. Nanostructural characterization of catfish skin gelatin using atomic force microscopy. Delivery of Functionality in Complex Food Systems: Physically-Inspired Approaches From Nanoscale To Microscale. Amherst, MA, Oct. 8-10. (Abstract)
- Yang, H., Wang, Y., Regenstein, J., and Rouse D. 2007 Nanostructural characterization of catfish skin gelatin using atomic force microscopy. J. Fd. Sci.72(8): C430-C440.
- Zhou, P. and Regenstein, J.M. 2007. Chapter 13: Collagen and gelatin from marine by-products. In. Maximising the Value of Marine By-products. F. Shahidi (ed). Woodhead Publishing Ltd., Cambridge, England, p. 279-303.
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Progress 01/01/06 to 12/31/06
Outputs
Because of an absence of funding, no work was done on Alaskan pollock. However, we have begun to work with a group of universities in Alabama to help them apply our knowledge to catfish gelatin production. By working with folks in Alabama, we hope to share our accumulated knowledge.
Impacts
The pork industry often claims that it uses everything but the 'oink'; since fish are quiet we can do better. The total utilization of fish waste would encourage a more sustainable use of this environmentally important food stuff. The potential impact of using fish gelatin in the food supply could be quite significant in the food industry by making more kosher and halal products available, and in allowing the food industry to optimize gelatin containing products not only for gel strength and viscosity but to add melting point as a new, more flexible parameter to consider. And the fishing industry would be able to get a better return on their total investment.
Publications
- Zhou, P., S.J. Mulvaney, and J.M. Regenstein. 2006. Properties of Alaska Pollock Skin Gelatin, a Comparison with Tilapia and Pork Skin Gelatins. J. Food Sci. 71:C313-321
- Lokuruka, M.N.I., and J.M. Regenstein. 2005. Icing Practices' Impact on Scombrotoxin Formation in Atlantic Mackerel. J. Aquatic Food Product Technology 14(4): 23-36.
- Zhou, P., and J.M. Regenstein. 2006. Determination of Total Protein Content in Gelatin Solutions with the Lowry or Biuret Assay. J. Food Sci., C474-479.
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Progress 01/01/05 to 12/31/05
Outputs
Gelatin is an important functional biopolymer widely used in foods to improve elasticity, consistency, and stability. However, most commercial gelatins are made from pork or non-religiously slaughtered beef that makes it unacceptable for Jews and Muslims; some consumers are also concerned about BSE. Alaska pollock, a kosher and halal fish species, accounts for over 1/3 of the U.S. domestic fish catch, and its skin is a by-product of fish processing that provides a very poor economic return. The objective of this study was to optimize gelatin extraction from Alaska pollock skin and to determine its properties and potential food applications. Pollock skin gelatin extraction was investigated with a modern statistically derived experimental design. The work suggested that a concentration of Ca(OH)2 at 0.12 mol/l during alkaline pretreatment, a concentration of acetic acid at 0.1mol/l during acid pretreatment, a pretreatment temperature of 2 degrees C and an extraction
temperature of 50 degrees C would give the best extraction. The amino acid analysis showed that pollock skin gelatin contained less hydroxyproline and proline than mammalian gelatin, which lowers the gelatin gel melting temperature of pollock gelatin compared to commercial warm-water fish gelatins and mammalian gelatins. The pollock gelatin has minimal breakdown components, which results in a higher viscosity. The gel strength of pollock gelatin was lower than those of high quality warm-water fish gelatins and mammalian gelatins, but increased faster with decreasing temperature. The texture of pollock gelatin in gelatin desserts suggested that pollock gelatin desserts had a higher cohesiveness compared to gelatin desserts made from high bloom tilapia gelatin or pork gelatin. Pollock gelatin dessert had a lower melting temperature and narrower melting transition region, and was more viscous after melting. In conclusion, pollock skin gelatin with relatively high yield and good
functional properties could be obtained by optimizing extraction conditions. The gelatin desserts made from pollock skin gelatin might not only provide a promising solution for kosher and halal food product development and for consumers with health concern, but also provide some unique properties such as a lower melting temperature that might provide new opportunities for product development.
Impacts
The pork industry often claims that it uses everything but the 'oink'; since fish are quiet we can do better. The total utilization of fish waste would encourage a more sustainable use of this environmentally important food stuff. The potential impact of using fish gelatin in the food supply could be quite significant in the food industry by making more kosher and halal products available, and in allowing the food industry to optimize gelatin containing products not only for gel strength and viscosity but to add melting point as a new, more flexible parameter to consider. And the fishing industry would be able to get a better return on their total investment.
Publications
- Zhou P. and Regenstein J.M. 2005. Effects of Alkaline and Acid Pretreatments on Alaska Pollock Skin Gelatin Extraction J Food Sci pp. C392-396
- Zhou P. 2005. Gelatin from Alaska Pollock Skin. Ph.D. Thesis, Cornell University, Ithaca, NY
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Progress 01/01/04 to 12/31/04
Outputs
Gelatin is an important functional biopolymer widely used in foods to improve elasticity, consistency, and stability. However, most commercial gelatins are made from pork or non-religiously slaughtered beef that makes it unacceptable for Jews and Muslims; some consumers are also concerned about BSE. Alaska pollock, a kosher and halal fish species, accounts for over 1/3 of the U.S. domestic fish catch, and its skin is a by-product of fish processing that provides a very poor economic return. The objective of this study was to optimize gelatin extraction from Alaska pollock skin and to determine its potential food applications. Pollock skin gelatin extraction was investigated with a modern statistically derived experimental design. The work suggested that a concentration of Ca(OH)2 at 0.12 mol/l during alkaline pretreatment, a concentration of acetic acid at 0.1mol/l during acid pretreatment, a pretreatment temperature of 2C and an extraction temperature of 50C would
give the best extraction. The amino acid analysis showed that pollock skin gelatin contained less hydroxyproline and proline than mammalian gelatin, which lowers the gelatin gel melting temperature of pollock compared to commercial warm-water fish gelatins and mammalian gelatins. The pollock gelatin has minimal breakdown components, which results in a higher viscosity. The gel strength of pollock gelatin was lower than those of high quality warm-water fish gelatins and mammalian gelatins, but increased faster with decreasing temperature. The texture of pollock gelatin in gelatin desserts suggested that pollock gelatin desserts had a higher cohesiveness, but lower hardness and gumminess compared to gelatin desserts made from high bloom tilapia gelatin or pork gelatin. Pollock gelatin dessert had a lower melting temperature and shaper melting transition region, and was more viscous after melting. In conclusion, pollock skin gelatin with relatively high yield and good functional
properties could be obtained by optimizing extraction conditions. The gelatin desserts made from pollock skin gelatin might not only provide a promising solution for kosher and halal food product development and for consumers with health concern, but also provide some unique properties such as a lower melting temperature that might provide new opportunities for product development.
Impacts
This work is meant to provide the food industry with a new kosher and halal ingredient obtained as a byproduct of fish processing. Hopefully a win-win for everyone.
Publications
- Lokuruka, M.N.I. and Regenstein, J.M. 2004. Biogenic Amines in Iced and Temperature-Abused Tropical Fish: A Comparative Study with Temperate Atlantic Mackerel. J. Aquatic Fd. Prod. Tech. 13(1):87-99.
- Regenstein, J., Goldhor, S. and Graves, D. 2003. Increasing the Value of Alaska Pollock Byproducts. In Advances in Seafood Byproducts, AK Sea Grant College Program (AK-SG-03-01).
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Progress 01/01/03 to 12/31/03
Outputs
Gelatins from cold-water fish, due to their lower hydroxyproline content, usually have poor gelling ability and connot gel at 10C, the standard temperature for bloom determination. Alaskan pollock is an important fishery resource and accounts for over one third of the US fish catch. The objective of this study was to determine the chemical and physiochemical properties of PSG, and compare it with gelatins from other sources. Alaskan pollock skin was pretreated with 0.1 M Ca(OH)2 and 0.1 M acetic acid at 2C, then extracted with distilled water at 50C for 3 h and freeze-dried. Gel strengh was determined by the bloom method; viscosity using a Cannon-Fenske viscometer at 60C; molecular weight distribution by SDS-PAGE; hydroxyproline (Hpro) by the Woessner method; and the gel melting point using a heating rate of 0.20.4C per min. PSG contained about 7 percent HPro, which is similar to other cold-water fish gelatins (CFG), but lower than warm-water fish gelatins (WFG) and
mammalian gelatins (MG). The major protein fractions in PSG were the alpha, beta, and other oligomers. The gel strength of PSG was about 100 bloom at 10C, and increased much faster with decreasing temperature than WFG and MG. The gel melting point of PSG was 20C, lower than WFGs, and MGs. However, the viscosity of PSG was about 120 mps, much higher than all the other gelatins. These results suggest that because of the low HPro content and larger polymers, the physiochemical properties of PSG are different from WFGs and MGs. The total gelatin is often determined by the Lowry or Biuret method, with commercial gelatin as the standard. However, gelatins from different sources with different molecular weights (MW) may vary in 'protien color.' Our objective was to determine whether the choice of standard affects both total protien assays. The color responses at 650 nm for Lowry or 540 nm for Biuret for cod skin gelatin (CSG) and pork skin gelatin (PSG) as standards was determined. The
reference factor (RF) was the ratio of concentration by standard curves to the concentration by dry weight. MW distribution was determined by SDS-PAGE; Hpro by the Woessner method; T by measuring the viscosity change with temperature. The standard curves for the reference gelatins showed significant variation. Using CSG as the standard resulted in a more accurate determination for cold-water fish gelatins (RF, 0.96 to 1 for both methods), but less accurate for mammalian gelatins (RF, Lowery:0.61 to 0.63 and Biuret: 0.82to 0.84). However, using PSG as the standard resulted in a less accurate determination for cold-water fish gelatins (RF, 0.98to 1.03 for both methods). The difference in Hpro content, which affected the T of gelatins, correlated with the variation in color response. These results suggest that for the accurate determination of total gelatin protein, a gelatin from a similar source should be used.
Impacts
By increasing the value of the by-products of commercial fishing, the industry can hopefully make more money while creating less waste. This should also be environmentally beneficial and will provide the consumer with some new and unusual food choices.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
The roes and the stomachs are sold profitably in Asian markets. All other viscera are put into the meal operation, with the exception of livers, which are cooked separately. After cooking, the liver solids are added to the meal cooker. The liver oil is decanted off, added to the oil separated from the meal stickwater, and burned in the plant's boilers. At this time, the value of the oils as fuel outweighs any other use. Since heat degrades the feed value of the oil, and since prices of high quality fish oil are expected to rise in aquaculture markets, oil research centered on increasing the quality of the product. It was possible to demonstrate that liver oil could be separated at room temperature, following disruption of liver tissue by blending. It was also possible to demonstrate that the deep red color of oil separated from the body oil is due to its astaxanthin content. Both the cold treatment of liver oil and the astaxanthin content of body oil may lead to
increased value in the marketplace. Dry meal is expensive to produce, but relatively cheap to ship. In investigating potential local uses for fully wet viscera, hydrolysates that could be incorporated into fishing baits were produced. Bait has been manufactured using these hydrolysates and will be tested shortly. Gelatin is an important functional biopolymer widely used in foods to improve elasticity, consistency, and stability. Gelatins from pigskin and cattle hide have been characterized. However, extraction of gelatins from fish skin, which may be an alternative source that is acceptable for kosher (Jewish) and halal (Muslim) products, and as an alternative for markets concerned about BSE, have not been as well studied. The objective of the study was to determine the appropriate extraction process to obtain pollock skin gelatin. The results showed that the type and concentration of base and acid during pretreatment, and the extraction temperature and time strongly influenced the
total yield and rheological properties. The pretreatment of fish skin by using 0.1N Ca(OH)2 or NaOH with 0.05N acetic acid or 0.025N citric acid improved the gel strength of extracts. At 40C and up to 180 min, increasing extraction temperature and time increased the total yield of gelatins, with little effect on gel strength. However, further increasing extraction time and temperature would decrease the gel properties of extracts. The total yield of gelatin from pollock skin was more than 12 percent with a hydroxyproline content around 7 percent. These results demonstrate that the extraction of gelatin from pollock skin is mainly depended on pH, temperature, and extraction time. Gelatin with relatively high yield and good rheological properties can be obtained by optimizing extraction conditions.
Impacts
(N/A)
Publications
- No publications reported this period
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