Progress 10/01/09 to 09/30/14
Outputs
Target Audience: The target audience this reporting period were food industry professionals interested in various ways of having products maufactured for retail sales. Amother group were food industry scientists seeking a better understanding how inovation in the food industry has evolved. Over the course of the project sinces its last revision in 2009 the target audinec were indivdiual interested in modification of the casein micelle, behavior of beta glucan in fluid mmmilk systems and various redox materials impact in dough systems. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? This project in the past year lead to two individuals completing an MS degree in Food Science. This will help to further their careers in the food industry. In previous years of project threeindividuals completed MS degrees. How have the results been disseminated to communities of interest? Theindividuals presented open seminars in the Food Science and Nutrition Department (in FSCN 8310). These seminars are recorded and available to the public. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Main items accomplishments in this time period were the writing of two Plan B MS papers which will aid the food industry to produce better and safer food products. During the duration of the the project the following was accomplished: 1) Data indicates that barley beta glucan can be used in dairy systems as a gelling agent. Previously it had been shown that barley beta glucan is incompatible with the caseins in milk causing phase separation due to depletion flocculation. Results indicate that using barley beta glucan molecules of reduced size can prevent this. 2) Evaluate the interaction of shear temperature with barley beta glucan at various levels in non fat milk at various concentrations. The model developed was used to target optimal processing conditions and amounts of barley beta glucan for application in the stabilization of chocolate skim milk. 3) A reliable, inexpensive and highly reproducible method to obtain gram quantities of fully dephosphorylated bovine beta casein was developed. Analyses were conducted that indicted the protein produced was virtually free of phosphate groups. As expect a significant reduction in calcium binding by this protein occurred. Also, the conformation of the secondary structure was drastically altered. 4) In a bread system various redox agents (bromate, azodicarbonamide, ascorbic acid, proprietary enzyme blend, L-cysteine, and sorbic acid) were for their impact on optimum mixing time, loaf volume (defined as height) and flavor. Overall it was determined it is possible to produce a quality bread with more natural redox agents like sorbic acid,
Publications
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Progress 01/01/13 to 09/30/13
Outputs
Target Audience: The project focussed on providing information to the food processing community including, student in food related areas, faculty and food industry personnel. Changes/Problems: No changes are anticipated. What opportunities for training and professional development has the project provided? This project in the last year provided to individuals with the opportunity to complete MS degrees and thus further their knowledge and allow them to move forward in their careers. Both have taken new jobs since completing their degrees How have the results been disseminated to communities of interest? Resluts were presented in seminar form in the Food Science and Nutrition Department. These seminars are recored and can be accessed via the department' web sit. What do you plan to do during the next reporting period to accomplish the goals? As stated above a project to evaluate the impact of cheese age on the characteritics of process cheese made from it is being designed.
Impacts
What was accomplished under these goals?
The above two projects are still on going with respect to final data analysis and publication. Two other projects were undertaken which lead to the completion of two Plan B MS degrees. The first of these projects was a comprehensive review of the different ways that development of consumer food products is done. These paper contrasted the more tarditional approach to food product development which is that of doing virtually all of the work in house by a particular company. An examples of such companies would General Mills, General foods etc. The other type of approach is to us various vendors to aid in the development of products. This is used by a company like Target Corporation. In this case the product development scientists of the company work with vendors to develop the products sold under the companies private label. This would include, but not limited to sensory specialist, pacaging professional and individuals at the plants where the actual product is being produced. Another aspect of food product development covered was the use by both in house and private lab companies of contarct packaging companies. The second major project looks at looks at the impact of various dough improvers on loaf volume of bread. Basically the finding of this study (for materials uses) was that there was only limited impact of the improvers. Currently a project is being designed to evaluate the impact of the age of cheese has on the characteristics of process cheese made from it.
Publications
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: There were two main outputs from the project this year. One was a literature review on the status of redox agents in the bread industry. (Redox agents are used to strengthen dough structure.) Second, experiments were conducted to evaluate the effectiveness of replacing high risk additives (ones which could be banned in the near future) with safer ones. A standard white bread formula with no added redox agents was used as a control. The redox agents evaluated were: bromate, azodicarbonamide, ascorbic acid, proprietary enzyme blend, L-cysteine, and sorbic acid. The samples were evaluated for optimum mixing time, loaf volume (defined as height) and flavor. The sample using a combination of bromate, azodicarbonamide, ascorbic acid and enzymes had the shortest mixing time of seven minutes and thirty second while the control took the longest at eleven minutes. With the exception on the control and the sample with azodicarbonamide and enzymes the loaf volumes were within half a centimeter of each other. No flavor differences were noted among the various samples. Based on the results it is possible to produce a quality bread with more natural redox agents like sorbic acid, enzymes and ascorbic acid. Dissemination: Results from the portion of this project dealing with redox agents in bread system was presented as a public seminar on October 31 as part of the Food Science and Nutrition Department's seminar series. It was also recorded at this time and is archived in the department's seminar series PARTICIPANTS: Todd Bauer TARGET AUDIENCES: People who have an interest in theproduction of quality bread products with a minimum of additives being used PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Basically, what was found was that it is possible to use various combinations of redox agents to produce satisfactory breads.
Publications
- No publications reported this period
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Work was conducted to develop a method to fully dephosphorylate bovine beta casein. Product produced using this method was then used in studies of the secondary structure of the beta casein as well as the calcium binding ability of the product. FTIR spectroscopy was also done to study the secondary conformation of the dephosphorylated protein. A model of the impact of shear temperature on the gelling time of barley beta glucan was developed using a central composite design. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Results will be of use to individuals looking a novel protein to use in food applications. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
A reliable, inexpensive and highly reproducible method to obtain gram quantities of fully dephosphorylated bovine beta casein was developed. Analyses were conducted that indicted the protein produced was virtually free of phosphate groups. As expect a significant reduction in calcium binding by this protein occurred. Also, the conformation of the secondary structure was drastically altered.
Publications
- Jelen, P., P. Dejmek, D. Everett, A. Kelly, P. Roupas, D. Smith, and T. Coolbear. 2011. The next decade of International Dairy Journal in the electronic age of scientific publishing. International Dairy J. 21:1.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: OUTPUTS: This year the hypothesis was tested that the temperature of shear will significantly change the gelling time of barley beta glucan. To prove this hypothesis an experimental design was created to evaluate the interaction of shear temperature with barley beta glucan at various levels in non fat milk at various concentrations. The model developed was used to target optimal processing conditions and amounts of barley beta glucan for application in the stabilization of chocolate skim milk. Verification of these conditions should help the use of barley beta glucan as a food ingredient. Modification of casein micelles by dephosphorylation is in the planning stages. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: The target audience for this work will be the food industry professionals who utilize dairy products and need a novel gelling agent. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The results are promising in that they indicate barley beta glucan may give the food industry a new naturally occuring gelling agent. Also, of interest is the fact use of barley beta glucans may lead to increased health claims.
Publications
- Jelen, P., Dejmek, D., Everett, D., Kelly, A., Roupas, P., Smith, D., Wouters, J., and Coolbear, T. 2010. International Dairy Journal enters its 20th year amidst dynamic changes in editorial focus. International Dairy Journal, 20:1-2.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Project was revised during this past year. Initial data indicates that barley beta glucan can be used in dairy systems as a gelling agent. Previously it had been shown that barley beta glucan is incompatible with the caseins in milk causing phase separation due to depletion flocculation. Results indicate that using barley beta glucan molecules of reduced size can prevent this. Further work is being planned to verify this. Modification of casein micelles in milk protein concentrates is in the planning stages. PARTICIPANTS: At this point there are no relevant participants other than the PI. TARGET AUDIENCES: The target audience for this work will be the food industry professionals who utilize dairy products and need a novel gelling agent. PROJECT MODIFICATIONS: Since just revised no modifications at this time.
Impacts
At this point there are really no outcomes that are concrete enough to identify an impact. The results are promising in that they indicate barley beta glucan may give the food industry a new naturally occuring gelling agent.
Publications
- Jelen, P., Dejmek, D., Everett, D., Kelly, A., Roupas, P., Smith, D., Wouters, J., and Coolbear, T. 2009. International Dairy Journal shares concerns about plagarismin in scientific publications, International Dairy Journal, 19:1-2.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: During this period outputs have included serving as Editor for the International Dairy Journal, serve as judge of various state cheese and butter contests, teaching of two short course (Applied Dairy Chemistry and Principles of Cheese Making), consultant to the North Central Cheese Industries Association Board of Directors, and Associate Director of the Midwest Dairy Center. PARTICIPANTS: Short courses and conferences developed as part of project activities impacted processors and researchers. TARGET AUDIENCES: The target audiences varied from processors impacted by short courses and conferences (NCCIA)to researchers as impacted by editorial work and projects selected for research funding by Dairy Center. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
As editor I have impacted the flow of knowledge in the area of dairy products by assuring the only quality research is published. In the capacity as judge comments on the quality of the products submitted is returned to the person making the entry, which lead to better quality produces being produced. Short course instruction aid in disseminating practical diary knowledge to those individuals working closely with production of products for the consuming public. Working with NCCIA aids this group in formulating better programs for their members. Finally, as Assoc. Director of the Dairy Center I impact the selection of project undertake as well as facilitate the dissemination of knowledge to farmer member and processors who can put this information to practical use.
Publications
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Progress 01/01/07 to 12/31/07
Outputs
The knowledge acquired during the life of this project has been in a number specific ways: 1) Knowledge has been shared with two audiences in short course format. Cheese Makers course at the University of Wisconsin at River Falls which leads to becoming a licensed cheese maker in the State of Wisconsin. The other course Applied Dairy Chemistry is taught at the University of Wisconsin at Madison. 2) Critique of cheeses submitted to the various cheese contests in the State of Minnesota. 3) Serve as Editor for the International Dairy Journal, one of the top ranked journals in the food science area.
Impacts
Major outcome for the year was keeping the Department of Food Science and Nutrition operating as the Interim Department Head.
Publications
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Progress 01/01/06 to 12/31/06
Outputs
Aggregation properties of alpha casein were investigated under various conditions using cryogenic transmission microscopy (Cryo-TEM) and small and wide angle x-ray scattering (SWAXS). In a one percent solution of protein, micelles with what appear to be colloidal calcium phosphate clusters were observed with the Cryo-TEM. In .03 percent solutions of casein 20 to 30 nanometer micelles of alpha casein are detected. One was also able to observe the formation of larger micelles and the disruption of the micelles as the pH of the system is altered. By use of SWAXS the development of various types of calcium phosphate crystals was observed in conjunction with the protein micelles. The dominate crystal form was orthorhombic. Studies also continue on the impact of whey source on the protein profiles found in whey products.
Impacts
A better understanding the aggregation of the casein proteins has potential major impacts various dairy products especially fermented products like cheese and yogurt. These product are themselves aggregates of casein by the knowledge developed from this study it may be possible to increase yields of these products a well as alter product characteristics.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
A project currently under way deals with the composition and physical properties of whey protein concentrate (WPC) and whey protein isolate (WPI) produced from various sources of sweet cheese whey: bleached and unbleached Cheddar and mozzarella. To ensure that any differences determined among the sample were due to whey source and not processing, whey was acquired directly from a cheese manufacture and transported to the Food Science and Nutrition Department pilot plant for processing. Ultra filtration followed by spray drying was used to produce a 35% WPC. The WPI was produced by use of ultra filtration used in combination with diafiltration followed by spray drying. The samples produced were then frozen prior to analysis. All processing runs were done in duplicate. All samples were analyzed for fat, total protein, lactose and moisture. In addition, the whey protein nitrogen value was determined. As expected, the mozzarella samples had a higher degree of denatured
protein. High Performance Liquid Chromatography was used to determine the amounts of the three primary whey proteins: alpha lactalbumin, beta lactoglobulin, and bovine serum albumin. Also, the amounts of the four primary caseins were determined: alpha sub s one, alpha sub s two, beta casein, and kappa casein. Initial results indicate the presence of the four casein proteins, but at levels too low for reliable quantification. The relative ratios of the whey proteins were as expected the same as in milk and differences among the various whey samples still need to be confirmed. Initial work on the determenation of the physical properties of the samples is currently being done. The Rapid Visco Analyzer is being utilized for not only initial viscosity measurements, but to determine the changes in viscosity with heating. The foaming properties (foam volume and foam stability) of 5 and 10 percent solutions will be determined using the method developed by Smith, which involves the sparging of
nitrogen through the solution in a jacketed cylinder with a sintered glass base. This allows for control of the gas volume to incorporate in the sample. Emulsification ability of the products can be done in a 5 percent v/v oil in water system with protein concentration from 0.1 to 0.5 percent.
Impacts
The data from this project will allow both the users and producer of whey concentrates and isolates to have a better understanding of possible sources of variation in these products.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
Barley beta glucan, which has potential health benefits, as a soluble fiber source aid in the prevention of cancer, in the human diet was studied to determine if it could be, substituted for kappa carrageenan the traditional stabilizer used chocolate milk. After preliminary studies indicated that it was possible to make this substitution, a more detailed study was conducted to optimize substitution conditions. The main objective of this study was to determine the proper conditions to get weak gel formation in the shortest period of time. A weak gel is needed to keep the cocoa powder particles from settling out of the milk, however this gel cannot be so strong as to give a curdled or spoiled appearance to the milk. To determine these conditions, this study used a central rotational design. The three variables that were studied in a skim milk system were: barley beta glucan (1-2%) and nonfat dry milk (2-7%) were added and the temperature of shear mixing ranged from
(6-40C). It should be noted the beta glucan powder used was in excess of 80% beta glucan and shear was applied by means of a homogenizer operating at 2000 psi. Gel formation in the samples was determined rheologically. Gel formation was defined as the point where the storage modulus and the loss modulus were equal, at a tan delta of one. This determination was made in linear visco-elastic region for the samples and at zero shear. The initial analysis of the results indicted that the nonfat dry milk had no impact on the gelling time and thus, it was converted to a covariate in the further analysis of the data. This analysis indicates that at a concentration of 1.6% beta glucan and a shear temperature of 6.85C a weak gel formed almost instantly (approximately 2 seconds). Based on these results chocolate milk was formulated (skim milk, sugar 6%, cocoa powder 1.0%, and beta glucan 1.0%). Beta glucan was lowered from the optimum indicated in the initial study because of the added viscosity
sugar would provide to the product. Rheological results indicated rapid gel formation and visual observations confirmed suspension of the cocoa powder particles had been achieved. Another study is currently being conducted to determine the impact of cheese whey source has the composition and functional properties of whey protein concentrates and whey protein isolates made from these whey sources. The samples being studied were made by membrane techniques and then spray dried. Whey sources include both bleached and unbleached Cheddar cheese whey and mozzarella whey. Tests to be conducted include protein profiles and functional tests such as rheological behavior and foaming. One last study currently being designed involves determining the parameters needed to produce high protein (85%) extruded products whey products. Parameters to be evaluated will include screw configuration, pressure and temperature conditions and the type of starch included with the whey protein.
Impacts
Data from this project will aid in the use a beta glucan in dairy systems both as a stabilizer as well as a functional nutritional ingredient. Completion of the whey study will aid end users in making choices about the source of whey they choose and will lead to more consistent products being produced.
Publications
- Merrill, Q.S. 2004. Process development for the application of barley beta glucan to chocolate milk as a stabilizer. M.S. Thesis. University of Minnesota, 98 pp.
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Progress 01/01/03 to 12/31/03
Outputs
A study of basic composition (proximate analysis), and protein and phospholipid profiles of industrial buttermilk powder samples was completed. Two sets of samples were collected. Group 1 consisted of thirteen samples, randomly collected from manufactures or suppliers in the US. Group 2 consisted of six samples, obtained from two manufactures with each supplying three samples. Proximate analysis revealed that over half of the samples contained greater than 4% moisture (standard calls for no more than 4%). Fat amounts while meeting the standard of greater than 4.5% covered a wide range (5.16% to 12.65%). Protein was in the range of 30.82% to 33.56%, which placed all of the samples greater than the standard of 30%. There is no standard lactose amount, but the range was 46.2% to 62.30, which points to the high degree of variability in the production of buttermilk powders. Protein profiles indicated some samples with greater amounts of whey proteins than others, which
might indicate whey cream contamination. Fifteen different Phospholipids were identified in the samples with Diacyl Glycophosphocholine being present in the greatest amount. Mineral analysis revealed one sample with approximately ten times the aluminum of the other samples. This probably was the result of buttermilk obtained from butter manufactured in an aluminum churn. In Group 2 samples there was good consistency with manufacturer, but some variation between the two. The fat average for one plant was 6% versus 9.5% for the other. Moisture varied form 4.9% to 4.1%. Lactose and protein values were relatively close for both manufactures. The protein and phospholipid profiles had values that fell within the range exhibited for the first group of samples. Two other projects are currently underway. One is studying the impact whey form different types of cheeses impacts the proteins present in whey protein concentrates produced from these different whey sources. The other project is
looking at the interactions between oat and barley beta glucans with milk proteins. Studies within this project are focused on impacts of heat, concentration of beta glucan and homogenization pressure on the rheological properties of the samples. Gel electrophoresis is being used to determine which of the milk proteins interacts with the beta glucan.
Impacts
Data from this project should aid both the producers and end users of buttermilk powder in understanding the variability present in the products on the market. With this better understanding of the variability, end users can more effiently and effectively use buttermilk product.
Publications
- WEE, J. K. 2003. Compositional characteristics of sweet cream buttermilk powder. M. S. Thesis. Univ. of Minnesota, St. Paul. 104 pp.
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Progress 01/01/02 to 12/31/02
Outputs
To try and determine the cause of variability in dried sweet cream butterminlk nineteen samples were analayzed. Proximate analysis revealed that there were significant differences(p<0.05)in the fat, protein, lactose, ash, and mositure contents of the samples. Analysis of the mineral content also revealed differences. The most interesting of these being a ten fold increase in the aluminum value for one of the samples. Protein profiles of the samples indicated some of the samples were high in whey protein indicating that whey cream was used for the production of the butter from which the buttermilk came. Phosopholipid profiles of the samples were conducted and these data are currently being analyzed. Work has begun to analyze whey protein concentrates and whey protein isolates made from different whey sources. The ojective of this work is to determine factors that lead to variability in these products.
Impacts
By understanding what is the cause of variability among buttermilk samples as well as whey products it will be possible for either processor to better control their processing system and thus produce more consistent products.
Publications
- Schaller-Povolny, L.A., and Smith, D.E.2002.Interaction of milk proteins with inulin. Milchwissenschaft. 57(9/10)494-497.
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Progress 01/01/01 to 12/31/01
Outputs
A method was developed to produce large quantities of fully dephosphorylated beta casein. This method utilizes milk beta casein produced by the method developed by Ward and Bastian. The beta casein is reacted with potato acid phosphatase for 72 hours. Removal of the phospahte groups from the beta casein was confirmed by Fast Liquid Chromatography, Inductively Coupled Plasma Atomic Emission Spectroscopy, and SDS and Polyacrylamide Gel Electrophoresis. The amount of dephosphorylation was greater than 99%. Calcium binding studies (conducted using a calcium specific electrode) indicataed that the dephosphorylated beta casein had significantly reduced ability to bind calcium as compared to the naturally occurring form of the protein. Secondary structures of the modified and native beta casein were compared using Fourier Transform Infrared Spectroscopy. The major difference noted was an increase in the loop or irregular portion of the modified protein. Studies are being
conducted to determine the cause of variability found among lots of dried buttermilk and whey protein containing products.
Impacts
Dephosphorylated beta casein can more closely mimic human beta casein, which contains significant amounts of dephosphorylated beta casein, and thus the better understanding of this modified milk protein should have future application in infant formula. Understanding the cause of differences in dried buttermilk and whey protein products will lead to production of more consistent product being offered for use as ingredients.
Publications
- Jaskulka,F.J.2001.Factors affecting the determination of the kinetic reaction rate of beta-lactoglobulin thermal denaturation. Ph. D. Thesis. University of Minnesota. 179pp.
- Schaller-Povolny, L.A.,and Smith, D.E.2001. Viscosity and freezing point of reduced fat ice cream mix as related to inulin content. Milchwissenschaft. 56: (1) 25-29.
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Progress 01/01/00 to 12/31/00
Outputs
Isolated beta-casein dispersions and emulsion model systems were characterized by interfacial tension measurements and creaming stability. Comparisons of beta-casein to sodium caseinate and whey protein isolate (WPI) were also made. Beta-casein's surface activity was comparable to sodium caseinate's and better than the WPI's. However, it exhibited the poorest creaming stability and showed an increased coalescence rate over time. A method using fluorescence laser confocal microscopy was developed to characterize the emulsion and droplet behavior over time. Literature data reporting the kinetic reaction rate order for the thermal denaturation of beta-lactoglobulin were reviewed using two statistical approaches. The results of the analysis showed that, for some data sets, the reaction rate order determined using R squared was not in agreement with the Box-Cox determination. Just as importantly, the Box-Cox transformation resolved that for most of the data sets analyzed,
the reaction rate order was indeterminate. Thus, the conflicting results reported in the literature on the thermal denaturation of beta-lactoglobulin could result from the statistical approach used to analyze the data and determine a reaction rate order. Three thermal denaturation studies were conducted using heated solutions of commercial beta-lactoglobulin. Fast Protein Liquid Chromatography (FPLC) anion exchange or gel-permeation chromotography were used to quantify changes in the remaining dimeric beta-lactoglobulin. Using the Box-Cox transformation approach, and associated 95% confidence interval, it was found that the data could be described by a first-order reaction equation. Published studies, using size-exclusion chromatography (SEC), have revealed that progressive heating of beta-lactoglobulin solutions initially results in the dissociation of beta-lactoglobulin dimers into monomers. In this study, early stages of heat-induced aggregation of beta-lactoglobulin were
investigated using FPLC SEC and matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). MALDI-MS indirectly confirmed the formation of monomeric protein as measured by FPLC SEC. However the concentration of beta-lactoglobulin could be increased or decreased depending on the solution pH, protein concentration, protein source, or mobile phase composition. Under certain conditions, there was no evidence of monomer formation in heated samples of beta-lactoglobulin at or near neutral pH when analyzed using SEC. A current study is investigating the effect dephosphorylation of beta-casein has on the secondary structure and the calcium binding of the protein. Also, factors that influence the functional properties of commercial whey and buttermilk products are being investigated. Of current interest in these products is the determination of the presence and amount of proteins and lipids, which would not be expected to be present in these products.
Impacts
The beta-casein studies will aid in the understanding of proteins. This will aid individual in determining if beta-casein product can be used in formulated foods. By better understanding the thermal behavior of beta-lactoglobulin, processors and end users of products containing this protein can better predict the resulting behavior of these products in foods and other applications.
Publications
- Afzal, I. 2000. An operational analysis of the quality assurance of a manufacturing facility and the development of a HACCP Program. M. S. Thesis Plan B. University of Minnesota. 43pp.
- Chang, I. A. 2000. Emulsification properties of beta-casein. M. S. Thesis. University of Minnesota. 75pp.
- Mauer, L.J., Smith, D. E., and Labuza, T. P. 2000. Effect of water content, temperature, and storage on the glass transition, moisture sorption characteristics and stickiness of beta-casein. International Journal of Food Properties. 3(2):233-248.
- Mauer, L.J., Smith, D. E., and Labuza, T.P. 2000. Water vapor permeability, mechanical, and structural properties of edible beta-casein films. International Dairy Journal. 10:353-358.
- Schaller-Polvolny, L. A., Smith, D. E., and Labuza, T. P. 2000. Effect of water content and molecular weight on the moisture isotherms and glass transition properties of inulin. International Journal of Food Properties. 3(2):173-192.
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Progress 01/01/99 to 12/31/99
Outputs
The potential interactions between inulin and the milk proteins were studied using polyacrylamide gel electrophoresis. The data indicated that in the presence of inulin, all of the casein proteins and beta lactoglubulin became insoluble and fell out of solution. Alpha-lactalbumin was the only milk protein studied that did not show an interaction with inulin. Effects of storage conditions on the secondary structure of beta-casein in powders, films, and solutions were determined. Fourier transformation infrared spectroscopy absorbance spectra were obtained for beta casein after the protein had been stored for 16 months at either -29C or 22.5C. Results indicated that the secondary structure did not change as a function of storage temperature, but was affected by the physical state of the protein. A method was developed to produce viable edible films on a laboratory scale. Edible films were made using glycerol and beta casein that had been stored as described above. Water
vapor permiability at 22.5C was determined for two relative humidity gradients (53 - 11 and 53 - 75 percent RH). Stress -strain curves for the mechanical property evaluation were obtained by the extension-film dynamic mechanical analysis method. Protein storage temperature did not significantly affect water vapor permiability or the elongation properties; however, films from beta-casein stored at -29C had higher ultimate tensile strength, modulus of elasticity, and yield strength than films made from 22.5C stored beta casein. Addition of citrate during the ultrafiltration of skim milk leads to the production of dried milk protein concentrate with greatly improved emulsion-stabilizing qualities. Emulsions stabilized with the modified milk protein concentrate had better creaming stability than a standard milk protein concentrate. The control product performed very poorly, where as the modified product performed as well as sodium caseinate. The modified product emulsions were also more
resistant to coalescence than the control. Again the modified compared favorably to sodium caseinate. Similar results were noted in floculation studies with the control product undergoing floculation, while the modified product and sodium caseinate did not. Currently sudies are being conducted on the emulsifying properties of beta casein. Also, research on the dephosphorylation of beta caein is being conducted.
Impacts
Protein interactions help explain differences in the texture of ice cream containing inulin and will result in the use of this ingredient in commercial food products. The research on modified milk protein concentrate and beta casein presents some practical and fundamental information which should lead to the use of these material in both foods and pharmaceutical products.
Publications
- FRESENBORG, K. A. 1999. Emulsification properties of a modified milk protein concentrate. M. S. Thesis. University of Minnesota. 70pp.
- MAUER, L. J. 1999 Properties of beta casein and edible beta casein films. Ph. D. Thesis. University of Minnesota. 94 pp.
- SCHALLER-POVOLNY, L. A. 1999. Selected physical and functional properties of inulin in ice cream. Ph. D. Thesis. University of Minnesota. 186 pp.
- KAMESWARAN, S. and SMITH, D. E. 1999. Rennet clotting times of skim milk based rennet gels supplemented with an ultrafiltered milk protein concentrate. Milchwissenschaft. 54 (10):546-550.
- SCHALLER-POVOLNY, L. A. and SMITH, D. E. 1999. Sensory attributes and storage life of reduced fat ice cream as retalted to inulin content. J. Food Sci. 64(3):555-559.
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Progress 01/01/98 to 12/31/98
Outputs
Glass transition temperatures and water sorption isotherms were determined for b-casein stored under various conditions. Significant differences were noted between protein which had been frozen versus protein stored at room temperature. Currently electron microscopy and secondary structure studies (using FTIR) are underway to determine the molecular differences noted in the initial studies. The microscopy studies indicate differences in the structure of the powder particles with the frozen particles being much smaller in size. Also, films made from the powders are different in appearance. Sensory studies determined that inulin substituted for 42DE corn sweetener produced a chewier and less icy reduced-fat ice cream. Glass transition temperatures and water sorption isotherms also indicated difference in the behavior of these two carbohydrate products. Size exclusion chromatography and gel electrophoresis (PAGE) experiments are currently being conducted to determine
which milk proteins interact with inulin to cause the differences noted in the sensory studies. Experiments studying the emulsifying properties of a modified milk protein concentrate as well as b-casein are currently underway. These experiments include rate of creaming, protein loading at the surface of the oil droplets in the model system, and surface and interfacial tension measurements. Preliminary results form an emulsion stability experiment indicate that the modified milk protein concentrate is able to produce emulsions from of comparable stability to sodium caseinate.
Impacts
(N/A)
Publications
- DYBING, S. T. and SMITH, D. E. 1998. The ability of phosphates or k-carrageenan to coagulate whey proteins and the possible uses of such coagula in cheese manufacture. J Dairy Sci. 81:309-317.
- DYBING, S. T., SMITH, D. E., ECKNER, K. F., and ZOTTOLA, E. A. 1998. Laboratory procedure for the manufacturing of Cheddar-type cheese varieties from 5x ultrafiltration retentates. Milchwissenschaft 53(7):377-380.
- SHERWIN, C. P., SMITH, D. E., and FULCHER, R. G. 1998. Effect of fatty acid type on dispersed phase particle size distributions in emulsion edible films. J. Agric. Food Chem. 46(11):4534-4538.
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Progress 01/01/97 to 12/31/97
Outputs
Water Vapor Permeability (WVP) was determined for whey protein films containing five fatty acids, myristic, palmitic, stearic, arachidic, behenic, and a film with no fatty acid. Films were tested using ASTM E96-80 method, at 53:11, 83:57, and 94:83% relative humidity gradients. WVP increased as chain length increased at 53:11, but no statistical differences were found at higher gradients. Dispersed phase particle sizes of the films were measured by polarized light microscopy and digital image analysis. Particle size increased as chain length increased. Mathematical models were developed to describe the mode of inhibition to water transfer that dispersed lipid particles imparted on the hydrophilic continuous phase matrix. Unique combinations of permeant path and phase interactions were found to govern the inhibition of water permeantion for each formulation. A reduced fat ice cream produced with inulin had increased chewiness when evaluated by sensory analysis. Over
the course of a six week storage study the inulin containing product exhibited less development of an icy texture. A modified milk protein concentrate (MMPC) produced by the addition of citrate during the diafiltration step exhibited enhanced emulsification properties. This characteristic was attributed to the increased amount of non micellar casein present in the product. Ongoing research includes; 1) further characterization of the MMPC; 2) defining the mechanism by which inulin enhanced chewiness and; 3) evaluation of the changes which occur in isolated beta-casein powder with storage time.
Impacts
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Publications
- SMITH, D. E. and BERGE, C. B. 1997. The effect of two antioxidants on the light stability of vitamin A in fluid milk. Milchwissenschaft 52 (10): 551-554.
- ZAHAR, M., SMITH, D. E., and HAMAMA, A. 1997. Manufacture of Jben, Moroccan fresh cheese from recombined milk. Milchwissenschaft 52 (11): 618-622.
- SOMAYAJULA, S. 1997. Determination of thermal conductivity of skim milk retentates and rennet gels by transient state method. M. S. Thesis. Univ. of Minnesota, St. Paul. 72 pp.
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Progress 01/01/96 to 12/30/96
Outputs
A study of the thermal conductivity of rennet gels produced from ultrafiltrationretentates was completed which resulted in the development of a modified line heat source method for the determination of thermal conductivity. Data from the project showed an increase in thermal conductivity with an increase in concentration of the retentate. A decrease in conductivity was noted as the temperature of the gel was increased. Adaptation of a retinol binding assay to determine extent of denaturation of beta lactoglobulin has nearly been completed. This assay will then be used to determine the kinetics of denaturation of the protein. Preliminary studies have been conducted on a number of projects: 1) It appears that production of whey protein edible films modified by the addition of fatty acids can be accomplished by use of a microfluidizer to mix the film components. This is then followed by the casting of the films on a Teflon surface. 2) Production of beta casein edible
films is also being worked on, current concerns for this project center on the conditions for drying the films. 3) Conditions for the production of modified milk protein concentrates has centered on the amount of citrate to add to destabilize the casein micelle and the parameters for the drying of the product after concentration of the proteins by ultrafiltration. For all three of the above projects work is being done on the methods which will be used to characterize the materials.
Impacts
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Publications
- ZAHAR, M. and SMITH, D.E. 1996. Adsorption of proteins at the lipid-serum interface in milk systems with various lipids. Int. Dairy J. 6:697.
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Progress 01/01/95 to 12/30/95
Outputs
Studies of ionic calcium in milk products lead to conclusions: 1) As raw milk stored at cold temps., an increase in ionic calcium content occurs. Requires a period of 60 hrs for equilibrium to occur. 2) Initially after heat treatment a decr. in ionic calcium occurs but upon storage the original equilibrium is reestablished. With this shift toward equilibrium following a pattern similar to that of raw milk. 3) Ultrafiltration caused initial decr. in ionic calcium, but after 24 hrs storage the level of ionic calcium increased to one approaching that of raw milk. Thermal denaturation of B-lactoglobulin (B-Lg) was measured using anion-exchange chromatography. A commercially avail source of enriched B-Lg whey protein isolate was further conc. through acidification (pH 4.2) and heating (65oC for 30 min.) in order to aggregate and remove other whey proteins present. Solutions were buffered to (pH 7.0) and heated to 70o, 80o, and 90oC for varying amounts of time (0-31.5 min.)
to produce irreversible denaturation and subsequent aggregation of B-Lg. Kinetics of reaction were determined. The linear crystal growth rate technique was applied to solutions of simple sugars and sweetener systems used in frozen dairy desserts. Data from these studies (very different growth rates were observed) are currently related to sensory eval. studies of the iciness of sherbets produced with different sweeteners systems. A method was developed for determination of thermal conductivity in milk gels ultrafiltration retentate.
Impacts
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Publications
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Progress 01/01/94 to 12/30/94
Outputs
Ultrafiltration was used to manufacture milk protein concentrates (MPC) which contained about 80% protein and 2% lactose. Four different sets of conditions were used in the production of the MPC powders: low and high heat pasteurization (163F versus 185F both for 17s) and two pH levels (6 and 6.5). Rennet coagulation studies, using a formagraph and dynamic rheometer, were conducted on reconstituted non-fat dry milk solutions supplemented with MPC to obtain final protein concentrations ranging from 4.65 to 6.25%. Rennet clotting times were not significantly influenced by the heat treatment of powder production. From the dynamic rheological experiments, the rennet gels with high heat MPC added had higher elastic moduli at the end of one hour. This increase may be due to an increase in the water holding capacity of the gel as a result of a greater denaturation of the whey proteins. An increase in protein concentration from 5.45% to 6.26% increased the rate at which the
elastic modulus increased, corresponding to the second phase of rennet gel formation. Microscopic studies of ice formation showed that significantly different ice crystal patterns are formed as a result of both the concentration of whey protein (0 to 8%) present in solution and the extent of denaturation of the whey proteins. An increase in either concentration or extent of denaturation resulted in a larger number of shorter ice crystal dendrites being formed.
Impacts
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Publications
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Progress 01/01/93 to 12/30/93
Outputs
Studies were conducted to further characterize the effect thermal denaturation of the whey proteins of milk has on the process of freezing in frozen dairy desserts and model systems. A sensory study of ice cream formulated with different milk proteins and processing temperatures found that the major protein source (nonfat dry milk, caseinates, and whey proteins), processing temperature (72C for 30 sec. versus 90C for 60 sec) and their interaction were significant determents in the development of iciness in the product. In general, differences in iciness among samples appeared to be established during initial ice crystal formation (i.e. during the freezing process). These differences were for the most part retained throughout storage; actual ice crystal growth rates, as perceived by the judges, appeared to be negligibly affected by the treatments employed for this study. It is hypothesized that the high degree of aggregation of denatured whey proteins in the more
severely heated samples acted as nucleating agents and thus reduced initial ice crystal size. Initial results from a microscopic study of ice crystal formation showed that significantly different patterns of ice formation resulted from both changes in the concentration of whey proteins present as well as from the extent of heat denaturation of the whey proteins.
Impacts
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Publications
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Progress 01/01/92 to 12/30/92
Outputs
The effect of heating time at 80C and concentration factor on the denaturation of -lactalbumin (-la) and -lactaglobulin (-lg) were studied in whole milk and whole milk ultrafiltered retentates (2X and 3X concentrations). After 5 min. the % denaturation of -la averaged from 15% in whole milk to 20% in 2X and 3X retentate, and the % denaturation of -lg was 46% in whole milk, 47% in 2X and 49% in 3X. After 30 min. the % denaturation of -la ranged from 70% in whole milk to 80% in 2X and 90% in 3X retentate, and the % denaturation of -lg was 90% in whole milk, 95% in 2X and 99% in 3X. The % protein denatured was determined using High Performance Liquid Chromatography. Solutions of 5.0% Whey Protein Isolate (WPI), with and without 5.0% added sucrose, were heated for various times at 65, 70, and 80C. All solutions displayed increased viscosity as they were subjected to more severe heat treatment. The most significant changes were observed at 70 and 80C. Compared with
solutions containing only WPI, the sucrose containing solutions had lower viscosities. Turbidity values, an indicator of protein aggregation, increased as a function of heating time and temperature for all samples, but did so less rapidly in the solutions containing sucrose. These turbidity data correlated with linear crystallization rates suggesting that whey protein aggregates may have acted as ice crystal nucleates.
Impacts
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Publications
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Progress 01/01/91 to 12/30/91
Outputs
Treatments to increase whey protein recovery during the rennet coagulation of concentrated UF retentates were screened. Viscosity measurements showed that optimum coagulation occurred after 90 min. at room temperature for whey protein concentrate solutions (14% protein, 20% total solids) treated with 0.20% sodium pyrophosphate and 0.15% calcium chloride at pH 6.3, 0.05% sodium hexametaphosphate at pH 2.5, or 0.05% kappa- carrageenan at pH 4.6. Treated concentrates were added to 4.8x UF retentates, mixtures set with rennet, and coagulums analyzed for curd tension, syneresis, and protein losses in the whey. Treatments were able to reduce protein losses in the whey at nearly 9%. Milkfat, butter oil, and corn oil were added to skim milk at 1% (vol/wt). Also systems of corn oil with added Vitamin A and Tween 80 or distilled monoglycerides were used at the same level. After processing, oil globules were separated as a cream. Protein and oil contents of the creams were
determined by Kjeldahl and Mojonnier methods respectively. RP-HPLC was used to determine the membrane protein profile. Amount of protein per gram oil increased while protein load (mg/m2) decreased with increase in homogenization pressure (10 vs 17 MPa). Added Vitamin A and emulsifiers significantly decreased the amount of adsorbed protein at the oil-serum interface. Caseins represented more than 97% of the total protein mass. Among whey proteins beta-lactoglobulin was the most dominant.
Impacts
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Publications
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Progress 01/01/90 to 12/30/90
Outputs
The effects of pH and heating time/temperature on the freezing rate of a 5% solution of whey protein isolate (>95% protein) with and without added sucrose (5%) were investigated. For the former, pH levels of 5, 6, 7, and 8 were utilized, while for the latter, time/temperature treatments included 65(degree)C and 70(degree)C for 0, 10, 20, and 30 minutes, and 75(degree)C for 10 min. All solutions in the time/temperature study were buffered to pH 7. ANOVA was performed and LSD used as the criterion for determining significant differences (p<0.05). Whey protein solutions at pH 8 froze significantly faster than those at pH 5, 6, or 7. Heating, both in the presence and absence of sucrose, also introduced significant differences in freezing rate. In solutions containing only whey protein, the greater the heat treatment, the faster the rate of freezing, even though higher heat treatments also increased solution viscosity. In the presence of sucrose, heating at 65(degree)C
retarded freezing rate as a direct function of heating time. Heating at 70(degree)C for 10 min induced the most significant retardation of freezing rate observed, however, this trend reversed after heating at 70(degree)C for longer periods. Vitamin A distribution among core of fat globule, fat globule membrane, and skim milk was investigated. Results showed the percentage of vitamin A localized in the core was in the range of 89 /+-/ 3.4% of the total vitamin A in milk with most of the remainder in the membrane.
Impacts
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Publications
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Progress 01/01/89 to 12/30/89
Outputs
A mathematical model to better predict the freezing point of ice cream was developed. The model is based on ninety different formulations in which percent milkfat and total solids were varied as well as the amount and source of milk solids not fat (nonfat dry milk, buttermilk, and whey) and sweetener (sucrose, 36DE corn syrup solids and 42 high fructose corn syrup solids). This method is more universal in its application than previously published methods. Research on the interaction of carbohydrate macro molecules (guar, carrageenan and xanthan gums) with dairy protein sources, as studied by viscosity, has shown that interaction is dependent upon gum and protein sources, concentration of gum, and heat treatment. Further analysis of the data is currently being done. Work with ultrafiltration retentates in the production of Cheddar cheese has shown that level and type of coagulant used (rennin or rennin: porcine pepsin) has no effect on cheese yield or body and texture
of the cheese as determined by Instron. A rapid high performance liquid chromatography method has been developed to quantify native vitamin A in milk and cream samples. This method will be used to study vitamin A location in both raw and pasteurized-fortified milks.
Impacts
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Publications
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Progress 01/01/88 to 12/30/88
Outputs
Research on vitamin A stability in fluid milk focussed on the partitioning of the vitamin within milk. Initial work has shown added or natural vitamin A may partition in a similar manner although their stabilities to light differ. Further, work in this area will attempt to elucidate the manner in which these two sources of vitamin A bind in milk. Studies of the gelling properties of ultrafiltration (UF) retentates have shown a rapid increase in gell strength when the protein content reached approximately 12%. The role of calcium in this gelling is currently being studied. The fate of whey proteins in Cheddar cheese prepared from UF retentates indicates both choice of enzyme coagulant and retentate concentration may play a role in whey protein hydrolysis. Quality attributes of cheeses made in this study are also being monitored. A mathematical model to better predict the freezing point of ice cream is under development. The model is based on ninety different
formulations in which percent milkfat and total solids were varied as well as the amount and source of milk solids not fat (nonfat dry milk, buttermilk, and whey) and sweetener (sucrose 36 DE corn syrup solids and 42 high fructose corn syrup solids). Experimentation to verify the model is currently being conducted. A comparison of two methods to determine fat destabilization in ice cream (Keeney's and Berger's) is currently being completed. Research on the interactions of carbohydrate macro molecules with dairy proteins in proceeding.
Impacts
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Publications
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Progress 01/01/87 to 12/30/87
Outputs
Research involved the characterization of nonfat dry milk in which 80% of the lactose was hydrolyzed and the product was then fermented (FHL-NFDM). When the FHL-NFDM was compared to nonfat dry milk, it was found to have lower foam volume and capacity, lower solubility and a distinctly different moisture sorption isotherm. A second study involved assessing how antioxidants (alpha tocopherol and ascorbyl palmitate) may stabilize vitamin A against photodegradation. Results showed that there was no stabilizing effect. Work was begun on the properties of skim and whole milk retentates. Initial data show that at low levels of concentration the retentates are stable to freezing but become unstable at concentrations over a factor of four. This work continues with present efforts centered on a study of the rheological properties of retentates. A comparative study of the various calculative methods and direct measurement techniques for the determination of the freezing
point of ice cream mix is being conducted. Data indicate poor agreement among these various means of determining freezing point. Current work in this area is attempting to elucidate the cause of this disagreement. A major study of carbohydrate macro molecule interactions with the dairy proteins is beginning.
Impacts
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Publications
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Progress 01/01/86 to 12/30/86
Outputs
Two studies were conducted during the year. The first involved characterizationof nonfat dry milk, in which 80% of the lactose had been hydrolyzed (HL-NFDM). When compared to nonfat dry milk (NFDM) on a compositional basis, HL-NFDM was similar. Physical properties of the two products, such as viscosity, emulsion capacity, and foam stability, were comparable while freezing points differed. Sensory analysis data showed the HL-NFDM had a sweetness equal to that of NFDM with 2% added sucrose. Similar sweetness information was obtained when the HL-NFDM and NFDM were used in ice cream, a breakfast drink, and cookies. The second study evaluated the effect of changes in homogenization pressure on sensory properties of ice cream. Results indicate good quality ice cream can be produced with pressures much lower than are presently being used. Also, data showed that emulsifiers, when added to the product, interfere with the intensity of vanilla flavor in the product. Three
studies are currently being conducted. The first involes characterizing HL-NFDM which has been fermented. Data being collected are similar to data collected for the comparison of HL-NFDM and NFDM. A second study is looking at the role of various dairy proteins in the perception of flavors, such as sweetness and vanilla. The third study is accessing what types of changes are occurring in milk proteins when they are subjected to the shear stresses involved in membrane processing of various dairy products.
Impacts
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Publications
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Progress 01/01/85 to 12/30/85
Outputs
A study of the effect of four dairy protein sources (nonfat dry milk, sodium caseinate, 35% whey protein concentrate and 35% whey protein concentrate with 80% of the lactose hydrolyzed) on perceived vanilla intensity and sweetness was completed. Sweeteners used included sucrose, high fructose corn syrup (HFCS) and aspartame. Viscosity of the systems were altered by addition of guar gum and locust bean gum. Differences in thickness determined by instrumental means (Haake viscometer) were not detectable by the sensory panelists. Vanilla intensity was perceived as more intense in the aspartame-sweetened systems that in HFCS sweetened systems. Changes in protein did alter the perception of sweeteners with sodium caseinate systems being less sweet than the other three protein systems. Three other studies are currently underway. The first involves determining if alteration of homogenization pressures can allow for less use of stabilizers and emulsifiers in a minimum
fat ice cream. Both sensory and analytical chemical methods are being used to identify differences among the products made. Second, a comparative study of methods to predict the freezing point of frozen desserts is being done. Of special interest is the effect various sweetener systems will have on the freezing point. Third, characterization of nonfat dry milk with 80% of its lactose hydrolyzed is being done. Emphasis is on determination of physical parameters such as sorption isotherms, hygroscopicity, browning rates, etc.
Impacts
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Publications
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Progress 01/01/84 to 12/30/84
Outputs
A study of the interaction of 3 combinations of guar and locust bean gums with 9combinations of sucrose, 36 DE corn syrup and 42% high frutose corn syrup (42 HFCS) in a minimum fat ice cream was completed. Apparent viscosity of ice cream mix is enhanced when high corn syrup levels are combined with a high guar to locust bean ratio. An adaption to the Instron of the DuNouy method for measuring surface tension was made. Utilizing this method no significant affects of sweetener-stabilizer combinations on the surface tension of ice cream mix were found. Sweetness and vanilla intensity were lowered when sucrose was replaced by 36 DE corn syrup but not when replaced by 42 HFCS. The combinations of sweeteners and stabilizers affected the shelf life of the ice cream, with products high in guar gum and 42 HFCS being the least stable. Probability statistics were able to predict the development of iciness in the ice creams and Weibull Hazard Analysis was appropriate for
predicting shelf life of the ice cream. Mixes high in locust bean gum were found to require less mechanical energy to freeze them than mixes high in guar gum. A study of the interaction of various sources of dairy protein (nonfat dry milk, caseinates, whey protein concentrate and whey protein concentrate with lactose hydrolyzed) and different sweeteners (sucrose, 42 HFCS and aspartame) on the perceived sweetness of combinations of these products is currently under way.
Impacts
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Publications
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Progress 01/01/83 to 12/30/83
Outputs
A study of the interaction of three combinations of guar and locust bean gums with nine combinations of sucrose, 36DE corn syrup and 42% high fructose corn syrup in a minimum fat ice cream formulation was conducted. The effects of the twenty-seven sweetener-stabilizer combinations on mix freezing point, rheological properties, homogenization and surface tension were measured. Additionally, the thermal conductivity and specific heat of both mix and finished product were determined. To assess differences in energy required to freeze the various formulae, energy utilization of the continuous freezer was monitored. Sensory evaluation studies of product iciness, gumminess, sweetness, and vanilla intensity were conducted. A storage study of heat shock stability is currently underway. Further experiments will involve meltdown and compression studies. In a related study, the effects of various sweeteners and levels of whey substitution on the rheological properties of the
mix were determined. Also various stabilizer systems and levels of whey substitution are currently being evaluated as to their effect on mix freezing point and rheological properties.
Impacts
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Publications
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Progress 01/01/82 to 12/30/82
Outputs
An initial series of experiments have been planned and preliminary work conducted to access data collection methods. The experiments are designed to study the interaction of three sweetening systems and various levels of galactomannan stabilizers (guar and locust bean gum) in ice cream. The ultimate objective being to maximize the quality of foods containing these ingredients, while producing these ice creams economically. Various physical properties of ice creams, both in the frozen and/or unfrozen state will be measured. For some of these measurements, i.e., viscosity, freezing point and thermal conductivity, adequate equipment and techniques are available. For other measurements adaptation of existing equipment is being done. A procedure to collect surface tension data using an Instron has been developed. Equipment to measure energy demands for freezing the product is currently being prepared and installed. Finally, sensory evaluation procedures are being
developed which will relate product quality to composition and physical properties.
Impacts
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Publications
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