Progress 07/01/04 to 06/30/07
Outputs
OUTPUTS: Cheddar cheese was manufactured in two separate experiments. In one experiment, cheese was made using the same starter culture but with two different coagulants, chymosin and Cryphonectria. parasitica rennet, either on their own or in combination at the normal level used in cheesemaking and at four times that level. In the other experiment, cheese was made using chymosin as the coagulant but with four different combinations of starter culture including Lactococcus and Lacobacillus helveticus cultures. From each experiment, half of the cheeses were aged at 42 F and the other half at 55 F. Proteolysis was followed using reverse HPLC of citrate-NaCl extracts of the cheese, and melt properties measured using a UW Meltmeter, and hardness, cohesiveness, and other textural properties measured with a TPA Analyzer. In addition, the changes in opacity of the cheeses as the cheese was heated were measured as an indication of the tendency of the proteins to aggregate because of
hydrophobic interactions.
PARTICIPANTS: D. McMahon was the PI for the project and supervised two graduate students conducting the research. One student, T. Rasmussen completed an MS degree and studied the effect of cultures. The other student, P. Joseph, did not complete his PhD research.
TARGET AUDIENCES: Scientists conducting research in the field of cheese chemistry and technical personnel in the cheese industry.
Impacts
Comparing the peptide profiles from the cheeses made using different coagulants, there were differences in the initial hydrolysis of the caseins even within the first week after manufacture, and during the first month of storage. Chymosin hydrolyzed alphaS1-casein quickest, C. parasitica rennet hydrolyzed beta-casein more rapidly. Elevated levels of the coagulant do change the pattern of hydrophobic proteins/peptides present. Cheeses having a higher level of coagulant (4X) and ripened at 55 degrees F had about 90% of the intact caseins and large hydrophobic peptides hydrolyzed in 2 to 4 months. Identification of the large hydrophobic peptides was not achieved which limited interpretation of the data. Changes in opacity as the cheese was heated were different based on use of chymosin or C. parasitica rennet. With chymosin, the L* value when the cheese was cold (10 C) was about 0.70, and it then decreased to about 0.40 at 50 C (previously presumed to be a function of
melting of fat) and then increased to 0.75 at 90 C. In contrast, with C. parasitica rennet the minimum in L* values at 50 C was not observed. Rather the L* slowly decreased from about 0.75 at 10 C to about 0.65 at 90C. This suggests that both the initial decrease in opacity below 50 C and the increase above 50 C are related to the level of intact beta-casein in the cheese. Only slight differences in proteolysis of the intact caseins and large hydrophobic peptides were observed when a Lactobacillus helveticus adjunct culture was used. Melting was not affected by the adjunct cultures while they did influence textural properties of adhesiveness and fracturability.
Publications
- McMahon, D. J. and B. S. Oommen 2008. Supramolecular structure of the casein micelle. Journal Dairy Science 91:in press.
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Progress 01/01/06 to 12/31/06
Outputs
Cheddar cheese was manufactured in two separate experiments. In one experiment, cheese was made using the same starter culture but with two different coagulants, chymosin and Cryphonectria parasitica rennet, either on their own or in combination at the normal level used in cheesemaking and at four times that level. In the other experiment, cheese was made using chymosin as the coagulant but with four different combinations of starter culture including Lactococcus and Lacobacillus helveticus cultures. From each experiment, half of the cheeses were aged at 6 C and the other half at 13 C. The aim of these experiments were to manufacture a series of cheeses that would age at different rates and thus have different proteolytic patterns and consequent melting properties. Proteolysis was followed using reverse HPLC of citrate-NaCl extracts of the cheese, and melt properties measured using a UW Meltmeter, and hardness, cohesiveness, and other textural properties measured with
a TPA Analyzer. In addition, the changes in opacity of the cheeses as the cheese was heated were measured as an indication of the tendency of the proteins to aggregate because of hydrophobic interactions. Comparing the peptide profiles from the cheeses made using different coagulants, there were differences in the initial hydrolysis of the caseins even within the first week after manufacture and during the first month of storage. Chymosin hydrolyzed alphaS1-casein quickest, C. parasitica rennet hydrolyzed beta-casein more rapidly, and the mixture elevated levels of the coagulant do change the pattern of hydrophobic proteins/peptides present. Cheeses having a higher level of coagulant (4X) and ripened at 13 C had about 90% of the intact caseins and large hydrophobic peptides hydrolyzed in 2 to 4 months. Changes in opacity as the cheese was heated were different based on use of chymosin or C. parasitica rennet. With chymosin, the L* value when the cheese was cold (10 C) was about 0.70,
and it then decreased to about 0.40 at 50 C (previously presumed to be a function of melting of fat) and then increased to 0.75 at 90 C. In contrast, with C. parasitica rennet the minimum in L* values at 50 C was not observed. Rather the L* slowly decreased from about 0.75 at 10 C to about 0.65 at 90 C. This suggests that both the initial decrease in opacity below 50 C and the increase above 50 C are related to the level of intact beta-casein in the cheese. Only slight differences in proteolysis of the intact caseins and large hydrophobic peptides were observed when a Lactobacillus helveticus adjunct culture was used. Melting was not affected by the adjunct cultures while they did influence textural properties of adhesiveness and fracturability.
Impacts
This research will increase our understanding of the mechanism by which cheese flows (melts) when heated, resulting in manufacturing companies being able to better design and manufacture cheeses to meet consumer preferences in pre-prepared meals. About 9 billion pounds of cheese is produced annually in the USA ($20 billion wholesale value). Two thirds of this cheese is cheddar and mozzarella cheeses in which melting is an important functional characteristic.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
Cheddar cheese was manufactured in two separate experiments. In one experiment, cheese was made using the same starter culture but with two different coagulants, chymosin and C. parasitica rennet, either on their own or in combination at the normal level used in cheesemaking and at four times that level. In the other experiment, cheese was made using chymosin as the coagulant but with four different combinations of starter culture including lactococcus and Lacobacillus helveticus cultures. From each experiment, half of the cheeses were aged at 42 F and the other half at 55 F. The aim of these experiments were to manufacture a series of cheeses that would age at different rates and thus have different proteolytic patterns and consequent melting properties . Cheese was made using a split-split plot design. The block treatment was the starter and adjunct cultures, split into 3 coagulant levels (chymosin, C. parasitica rennet and a combination of them), further split into
2 ripening temperatures (40 and 55?F). Sampling is being carried out at 1 week, 1, 2, 3, 4, 5 and 6 months. The cheese samples are being analyzed for proteolytic patterns using RP-HPLC and CE, soluble nitrogen at pH4.6 and 12% TCA, melt properties using a UW Meltmeter, and TPA with a TPA Analyzer. Cheese was extracted as previously described in a sodium citrate-sodium chloride extraction buffer and RP-HPLC was carried out as per the method developed. Comparing the peptide profiles from the cheeses made using different coagulants, there were differences in the initial hydrolysis of the caseins even within the first week after manufacture, and during the first month of storage. Elevated levels of the coagulant do change the pattern of hydrophobic proteins/peptides present. Future time points will be analyzed along with using CE methods to identify the proteins/peptides in each band, and will be correlated with melt and TPA data.
Impacts
It is known that the extent of melting of a cheese increases as the cheese is aged. By tracking the presence of large peptides in the cheese that are formed by hydrolysis of the intact proteins, and then subesquently hydrolyzed themselves, it is expected that we will be able to show how much of the proteins needs to be cleaved before its melting properties change. This will then help in understanding which portions of the protein molecules interact with each other to prevent melting.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
A method has been developed using reverse phase HPLC to separate large peptides extracted from cheese. Proteins and peptides were extracted from cheese using a citrate buffer, then concentrated using an ultrafiltration membrane filter with a molecular weight cutoff of 3 kDaltons. Differences in levels of these peptides were observed when a 1-week old cheese was compared to a cheese that had been stored for 6 months. Fractions from the HPLC separation were collected using a preparative for analysis for purity by capillary electrophoresis.
Impacts
It is known that the extent of melting of a cheese increases as the cheese is aged. By tracking the presence of large peptides in the cheese that are formed by hydrolysis of the intact proteins, and then subesquently hydrolyzed themselves, it is expected that we will be able to show how much of the proteins needs to be cleaved before its melting properties change. This will then help in understanding which portions of the protein molecules interact with each other to prevent melting.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
Influence of chemical composition of cheese on its functional properties was studied by injecting water, calcium chloride, sodium chloride, glucono-delta-lactone, or sodium citrate into cheese using high-pressure injection. A low calcium, low moisture part-skim mozzarella cheese was injected from 1 to 5 times, with either water or a 40% calcium chloride solution. Calcium content increased from 0.3% to 1.8%. After 42 d storage, cheese microstructure and functionality were analyzed. The uninjected cheese, had typical structure of stirred/pressed-curd cheese: protein matrix interspersed with areas that contained fat and/or serum. Injecting water increased the area of cheese matrix occupied by protein, decreased cheese hardness, but did not affect cohesiveness or melting of cheese. When calcium was injected, a decrease in cheese weight was observed that was manifested through syneresis. Moisture content and pH of the cheese decreased as well. Calcium injection decreased
area of cheese matrix occupied by protein. Cheese hardness increased, and cohesiveness and melting of cheese decreased. We concluded that adding calcium to cheese alters how the proteins interact, which is manifest as changes in cheese microstructure. Unsalted, Muenster cheese was injected 1, 3, or 5 times, with a 20% NaCl, increasing salt content from 0.1% to 2.7%, then analyzed after 40 d storage. Cheese pH, total and soluble calcium content were unaffected by injecting salt. The influence of salt on cheese functionality is most prevalent in the range of 0% to 0.5%, where adding salt increases cheese hardness, adhesiveness, and initial rate of cheese flow. Above 0.5%, salt had little affect on cheese properties. In addition, increased salt content did not cause an exchange of calcium, and soluble calcium remained constant. Thus, calcium-mediated protein interactions remain a limiting factor controlling the functionality of cheese. Cheddar cheese blocks were injected with a 20%
glucono-delta-lactone solution to reduce cheese pH, from 5.3 in the uninjected cheese to 4.7 after 5 injections. Lower pH increased the content of soluble calcium of cheese. Acidulant injection decreased cheese hardness and cohesiveness, and the cheese became more crumbly. The initial rate of cheese flow increased when pH decreased from 5.3 to 5.0, but it decreased when cheese pH was further lowered to 4.7. The final extent of cheese flow also decreased at pH 4.7. Lowering the pH of Cheddar cheese alters protein interactions, which then affects cheese functionality. At pH greater than 5.0, calcium solubilization decreases protein-to-protein interactions. In contrast, at pH lower than 5.0, the acid precipitation of proteins overcomes the opposing effect caused by increased calcium solubilization and decreased calcium content of cheese, and protein-to-protein interactions increase. Injecting sodium citrate solutions into Cheddar cheese increased citric acid content of cheese from 0.22
to 1.39% (after 5 injections) and caused phosphate solubilization. However, citrate injection had no effect on bound calcium, and thus the rate and extent of cheese flow were unaffected.
Impacts
This research provides a chemical basis for cheesemakers to understand how pH, calcium and salt content of cheese influences the cheese physical and functional properties. In the past it has been difficult to separate the influence of pH versus that of calcium because of the effect pH has on the solubulization of calcium during the cheese making process. Within the pH range of most rennet-set cheeses manufactured in the USA, pH 5.0 to 5.6, it is apparent from this research that the final calcium content of the cheese is the controlling factor, irrespective of cheese pH. It was also found that at normal salt levels (1.0 to 2.0% NaCl) there is little influence of salt content on cheese properties.
Publications
- Pastorino, A. J., C. L. Hansen, and D. J. McMahon. 2003. Effect of sodium citrate on the chemical compositon and structure-function relationships of cheese. J. Dairy Sci. 86:3113-3121.
- Pastorino, A. J., C. L. Hansen, and D. J. McMahon. 2003. Effect of pH on the chemical composition and structure-function relationships of cheese. J. Dairy Sci. 86:2751-2760
- Pastorino, A. J., N. P. Ricks, C. L. Hansen, and D. J. McMahon. 2003. Effect of calcium and water injection on structure-function relationships of cheese. J. Dairy Sci. 86:122-131
- Fife, R. L. 2003. The influence of fat and water on the melted cheese characteristics of mozzarella cheese. Ph.D. Dissertation, Utah State University
- Pastorino, A. J. 2003 Effect of chemical parameters on structure-function relationships in cheese, Ph.D. Dissertation, Utah State University
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Progress 01/01/02 to 12/31/02
Outputs
Casein Structure: Using high resolution transmission electron microscopy images to produce stereo images of casein supramolecules, we have developed a model for the casein supramolecule in which there is an open irregular organization consisting of nodes of calcium phosphate and interlocking strands of protein. The supramolecular structure results from the propensity of as1-casein, as2-casein, b-casein, and k-casein to interact via clusters of phosphoserine residues to calcium, via hydrophobic interactions with each other, and electrostatically with water. This model of the casein supramolecule satisfies the principles of self aggregation, interdependence, and diversity that are often observed in nature. Calcium phosphate functions as nodes from which various sized strands and rings of protein extend, and become interlocked with other protein strands at the calcium phosphate nodes. Synthesis of casein supramolecules in the mammary gland rely on a controlled synergy
between two concomitant aggregation processes. Calcium phosphate is formed into clusters because of its low solubility, and caseins are simultaneously undergoing polymerization because of their calcium sensitivity and hydrophobic nature. Precipitation of calcium phosphate is limited to formation of nanoclusters by binding of caseins via their phosphoserine side chains, and the polymerization of the caseins is limited to colloidal size by the chain-terminating influence of k-casein. Cheese Functionality: Low moisture part-skim Mozzarella cheeses were manufactured from 2%-fat milk and aged for 21 d. Treatments included cheeses made with one of three different strains of Lactobacillus delbrueckii ssp. bulgaricus in combination with a single strain of Streptococcus thermophilus. Although total proteolytic ability of these strains, as indicated by the o-phthaldialdehyde analysis, was similar in each of the three strains of L. bulgaricus, these strains exhibited different proteolytic
specificities towards the peptide, as1-CN (f 1-23). Moisture, fat, protein, salt-in-moisture, and moisture in non-fat substances content of cheeses made with Group I, III, and V strain were similar. Significant differences were observed in functional properties between cheeses manufactured using Group III and Group V strains. Cheeses made using Group I and Group III strains were similar in their meltability, hardness, cohesiveness, melt strength, and stretch quality. Meltability and cohesiveness increased with age while melt strength and stretch quality decreased with age for all cheeses. Additionally, HPLC showed total peak areas of water-soluble peptides was correlated to meltability and stretch characteristics of cheeses. Water-soluble peptide profiles of cheeses made using strains of lactobacilli that had different specificities toward as1-CN (f 1-23), paralleled profiles obtained when the cultures were tested in vitro. Thus, the breakdown of proteins in cheese can be controlled
through strain selection among lactobacilli. Protein specificity of the lactobacillal component should be considered when selecting starter culture strains to manufacture cheeses with defined functionality.
Impacts
A better understanding of how milk proteins are arranged, and how they interact will increase our ability to control product functionality. The information on milk provides a basis for understanding the changes that occur when milk is heated, acidified, or blended with other food ingredients. The information on cheese will aid cheese manufacturers in obtaining better process control in selecting the starter culture strains to use for making cheese.
Publications
- Fife, R. L., D. J. McMahon and C. J. Oberg. 2002. Test for measuring the stretchability of melted cheese. J. Dairy Sci.85:3539-3545.
- Oommen, B. S., D. J. McMahon, C. J. Oberg, J. R. Broadbent and M. Strickland. 2002. Proteolytic specificity of Lactobacillus delbrueckii subsp. bulgaricus influences functional properties of mozzarella cheese. J. Dairy Sci. 85:2750-2758.
- White, S. 2002. The effect of Lacctobacillus helveticus and Propionibacterium freudenreichii ssp. Shermani combinations on propensity for split defect in Swiss cheese, M.S. Thesis, Utah State University.
- Pastorino, A. J., C. L. Hansen, and D. J. McMahon. 2002. Effect of pH on chemical and functional properties of cheese. American Dairy Science Association Meeting, J. Dairy Sci. 85(Supp. 1):91 (Abstract)
- Oommen, B. S., and D. J. McMahon. 2002. Effect of method and time of hydration on structure of dried milk proteins. American Dairy Science Association Meeting, J. Dairy Sci. 85(Supp. 1):157. (Abstract)
- Oommen, B. S., and D. J. McMahon. 2002. Coagulation properties of skim milk fortified with various dried milk proteins. American Dairy Science Association Meeting, J. Dairy Sci. 85(Supp. 1):380. (Abstract)
- Pastorino, A. J, C. L. Hansen, and D. J. McMahon. 2002. Effect of salt on structure-function relationships of cheese. Annual Meeting, Institute of Food Technologists, Anaheim, CA. (Abstract 28-2)
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Progress 01/01/01 to 12/31/01
Outputs
Nonfat cheese was made according to a direct-acid, stirred-curd procedure. Cheese samples, at 4 C, were placed into glass bottles, which were sealed and heated. Once the cheese reached 10 C or 50 C, the bottles were placed on a scanner and color values measured. Applying heat increased cheese opacity. At 50 C the cheese was more opaque than at 10 C. The increase in temperature induced changes in cheese structure. Larger high-density protein aggregates and increased protein concentration in the protein matrix were observed in cheese at 50 C. Applied heat would favor hydrophobic interactions, and possibly, re-association of b-casein and calcium with the protein matrix, promoting protein-to-protein interactions. Thus, the protein matrix contracts, occupying less cheese matrix area and microphase separation occurs, causing serum pockets to grow in size, and microstructural heterogeneity to increase. It is proposed that the increased size of aggregates and heterogeneity of
the cheese at 50 C promote light reflection, thus increasing cheese opacity. Apparently, applying heat alters protein interactions in the cheese matrix, and this is manifest as changes in cheese structure. Such changes in structure help provide an understanding of changes in cheese opacity. Nonfat dry milk, sodium caseinate and calcium were reconstituted in water and examined by electron microscopy to compare their "micelle" structures. With short hydration times the sodium caseinate particles were still present as gel-like structure comprised of protein chains. As hydration continued individual protein particles of size 15 to 20 nm diameter were observed. Calcium caseinate solutions contained large protein particles that were spherical and 100 to 600 nm diameter. There were also numerous attached smaller particles that appeared to be protein that had not been completely hydrated. When nonfat dry milk powder was dispersed in water with only mild agitation, there was still evidence
that hydration of the powder was not complete. Most of the protein particles were present as casein micelles, although some were still present as agglomerates of micelles. The micelles formed from nonfat dry milk were not as spherical as the native micelles in milk or those formed from calcium caseinate. Singular protein strands were only present in the micrographs.
Impacts
Understanding the organization and structure of milk proteins in coagulated milk and milk products allows food manufacturers to have better process control while meeting market expectations.
Publications
- Dave, R. I., D. J. McMahon, J. R. Broadbent and C. J. Oberg. 2001. Reversibility of the temperature-dependent opacity of nonfat mozzarella cheese. J. Dairy Sci. 84:2364-2371.
- Pastorino, A. J., R. I. Dave, C. J. Oberg and D. J. McMahon. 2001. Temperature effect on structure-opacity relationships of nonfat mozzarella cheese. 96th American Dairy Science Association Meeting, J. Dairy Sci. 84(Supp. 1):5
- Oommen, B. S., D. J. McMahon, J. R. Broadbent and C. J. Oberg. 2001. Influence of proteolytic enzymes from thermophilic lactic acid bacteria on the functional properties of mozzarella cheese. 96th American Dairy Science Association Meeting, J. Dairy Sci. 84(Supp. 1):6
- Pastorino, A. J., N. P. Ricks, C. L. Hansen and D. J. McMahon. 2001. Salt and calcium distribution in injected cheese. 96th American Dairy Science Association Meeting, J. Dairy Sci. 84(Supp. 1):145
- Oommen, B. S., D. J. McMahon and W. R. McManus. 2001. A comparitive study of the microstructure of caseins in dried milk. 96th American Dairy Science Association Meeting, J. Dairy Sci. 84(Supp. 1):381
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Progress 01/01/00 to 12/31/00
Outputs
Casein micelle structure of milk and reconstituted milk was examined by transmission electron microscopy. Differences in structure were observed based on the protein source used to make reconstituted milk. Injection of calcium solutions into blocks of cheese to study the influence of calcium content on protein structure and functionality was completed. Cheese was injected calcium chloride solutions to increase the calcium content of the cheese from 0.3% to 1.8%. Injecting calcium into cheese induces syneresis. The resulting whey loss causes a decrease in weight of the cheese blocks. In contrast, when water is injected into cheese the cheese weight increases and up to 3% of water (w/w) can be incorporated into the cheese. When examined by electron microscopy it was observed that when calcium content of the cheese was increased there was a contraction within the protein matrix that formed the structure of the cheese. This agrees with previous observations on cheese
structure. When lower-fat cheeses are manufactured, it has been observed that these cheeses suffer from a loss of opacity and appear more translucent than full-fat cheeses. Translucency of nonfat cheese occurs when the cheese is cold. When nonfat cheese it becomes white and opaque. It returns to being translucent when the cheese is cooled. By studying nonfat cheese, the temperature-induced opacity observed during heating of cheese was shown to be completely reversible and is presumably a function of the temperature dependence of hydrophobic interactions between proteins. The opacity-transition temperature at which the cheese becomes opaque is dependent on the chemical composition of the cheese and the status of the proteins. Salted cheese must be heated to a higher temperature to induce opacity compared to unsalted cheese. Storage of cheese also increases opacity-transition temperature values and these can be related to the protein hydrolysis that occurs during storage.
Impacts
It is important for the development of new cheese products and for control of cheese making processes, that the fundamental parameters that control cheese functionality be understood. From this research we have demonstrated the importance of calcium in cheese functionality. It influences cheese firmness, cheese melting, and the color of cheese.
Publications
- McMahon, D. J. and C. J. Oberg. 2000. Manufacture of lower-fat and fat-free pizza cheese. U.S. Patent No. 6,113,953. Issued September 5, 2000.
- Pastorino, A.J., Ricks, N. P., Hansen, C.L., and D. J. McMahon 2000. Effect of water and calcium injection on structure-function attributes of Mozzarella cheese. Annual Meeting, Institute of Food Technologists, Dallas, Texas, June12-14, 2000 (Abstract 50-1)
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Progress 01/01/99 to 12/31/99
Outputs
During storage of mozzarella cheese, changes occur in the functionality of the cheese, especially with respect to its water-holding capacity and its meltability. The changes in water status of mozzarella cheeses was studied in relation to changes to cheese microstructure and functionality. A reduced fat (8% fat) mozzarella cheese and a control cheese with 19% fat were made and evaluated over 21 days of refrigerated storage at 4 C. Fat, protein, ash, salt, and water were measured on day 1. Meltability, total water, freezable water, and expressible water were measured on days 1, 7, 14, and 21. Even though the reduced fat cheese had a higher total water content than did the control cheese, the reduced fat cheese contained less water on a fat-free basis. The amount of water expressible at 25 C was higher in the control cheese than in the reduced fat cheese and was proportional to the fat content of the cheese. During storage, the expressed serum for both cheeses decreased
to zero by day 21. Based on changes observed in microstructure of a commercial mozzarella cheese (19% fat) during storage it was concluded that the expressed water was derived from water contained in the fat-serum channels that were interspersed throughout the protein matrix. The amount of bound water was lower in the control cheese than in the reduced fat cheese and was proportional to the protein content of the cheese. Bound water levels remained constant throughout storage. During storage of the commercial Mozzarella cheese, the fat-serum channels became smaller with the protein matrix expanding into the areas between the fat globules. By day 21, the fat globules were completely encased by the protein matrix. This expansion of the protein matrix in the commercial cheese occurred over the same time span as the decrease in expressible water of the experimental cheese, indicating that the protein matrix was absorbing the water originally located in the fat-serum channels. Because no
change in bound water was observed, the water that had been expressible at day 1 was being absorbed into the protein matrix as entrapped water. The meltability of both cheeses increased during storage at the same time as the percentage of entrapped water increased. Another change that occurs in mozzarella cheese that is related to its structure is a reversible heat-induced opacity. This is most evident in fat-free cheese and the temperature at which opacity transition occurs is dependent on salt content and age of the cheese. For 1 day old cheese, unsalted cheese has an opacity transition temperature of 15 C while for salted cheese it is 35 C. After 60 days storage the opacity transition temperature of the salted cheese increased to 62 C. Examination of the microstructure of the cheeses at 10 C and 50 C revealed that the change in opacity was a result of aggregation of the proteins upon heating. The reversibility of the aggregation upon cooling suggests it is a result of hydrophobic
interactions between protein molecules.
Impacts
The research conducted in this project is laying a foundation for understanding how the proteins in cheese influence the cheese's functional and physical properties. The length of time that mozzarella cheese must be stored before it is shredded or used as an ingredient in food manufacture is an important economic consideration for the cheese industry. This research provides a scientific basis for understanding the changes that occur during the first few weeks of storage.
Publications
- McMahon, D. J., R.L. Fife, and C. J. Oberg. 1999. Water partitioning in mozzarella cheese and its relationship to cheese meltability. J. Dairy Sci. 82:1361-1369
- McMahon, D.J. and C.J. Oberg. 1999. Deconstructing Mozzarella. Dairy Industries Int. 64 (7): 23, 25-26.
- Dave, R. I., McMahon, D. J., Oberg, C. J, and J. R. Broadbent. 1999. Factors and mechanism involved in temperature-dependent opacity of non-fat Mozzarella cheese. 94th American Dairy Science Association Meeting, J. Dairy Sci. 82(Supp. 1):D61.
- Dave, R. I., McMahon, D. J., and C. J. Oberg. 1999. Effect of salt and storage periods on temperature-dependent opacity of non-fat Mozzarella cheese. Annual Meeting, Institute of Food Technologists, Abstract 79A-37
- Dave, R. I., McMahon, D. J., Oberg, C. J, and J. R. Broadbent. 1999. Influence of coagulant concentration on proteolysis, meltability and rheology of 0, 10 and 20
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