Progress 03/29/16 to 03/29/21
Outputs
Target Audience:US cheese manufacturing industry is the target audience, especially those involved in product development and technical services. This group will be reached through presentations at dairy science meetings, cheese technology meetings and annual meeting of Western Dairy Center. Changes/Problems:None What opportunities for training and professional development has the project provided?Two graduate students completed MS programs of study. One visiting postdoctoral fellow and one visiting scholar-graduate study participated in the study. How have the results been disseminated to communities of interest?Presentations were made at the annual meeting of the American Dairy Science Association to students, and professionals from academia and the dairy foods industry. Presentations were made to interested dairy foods industry technical staff as part of the BUILD Dairy program of the Western Dairy Center. Presentations were made at the Global Cheese Technology Forum to professionals in the cheese industry. Presentations were made to interested dairy foods industry technical staff as part of the BUILD Dairy program of the Western Dairy Center. Two MS theses were completed and are available in USU Digital Commons. What do you plan to do during the next reporting period to accomplish the goals?This work has been completed
Impacts
What was accomplished under these goals?
Understanding cold gelation of recombined concentrated milk (RCM) and its rheological properties can help in designing process systems for using RCM as an ingredient in food applications. At pH 6.6, an RCM with 12% casein does not gel until cooled below 12°C and so would not interfere with cheese making. If the pH is higher than 6.6, then gelation occurs at higher temperatures unless the casein concentration is lowered. Cold gelation of RCM was thermally reversible, even when citrate was added to partially chelate calcium. Compared to cold-gelled highly concentrated-micellar casein concentrate (HC-MCC), the cold-gelled RCM, the casein micelles were less closely packed together and appeared as being partially dissociated. We propose that cold gelation of RCM occurs when protein strands that have been partially released from the casein micelles entangle, restrict their mobility and form a fine stranded gel network. Such a network consists of these fine strands of proteins as well as the modified casein micelles. Formation of a gel network that is dependent upon entanglement of protein strands that are only loosely-associated with the casein micelles would be favored when there is increased dissociation of casein micelles. When high levels (21 mmol/g casein) of calcium are added to RCM, the casein micelles were less dissociated but gelation was promoted, presumably through direct aggregation of casein micelles. Provided pH of RCM is not above the normal pH of milk, RCM at a casein level of 12% (wt/wt) has potential for use in cheese making. Concentrating milk by microfiltration has similar effects on RCT as does ultrafiltration, with no differences in RCT observed for milk containing ≥5.7% casein. While RCT remains similar, the firming rate does increase with casein concentration and the curd has G' values l00-fold of more higher than is typical for curd made by renneting milk. When pH of RCM was lowered to pH 6.2 prior to renneting, coagulation was accelerated as well as the rate at which curd firming occurred when measured relative to RCT. Analysis of microstructure of RCM and its coagulum confirmed that the increased curd firmness probably results from a stronger protein matrix formed by highly inter-linked protein strands in RCM curd. Overall, RCM with a casein level of 11 to 12% has potential for use in cheese making provided its higher viscosity compared to milk and its fast curd firming rate can be overcome. Thus, the same problems exist for high casein milks made using microfiltration as those already known for milk concentrated using ultrafiltration. Acidification of RCM at different casein concentrations as performed by mixing HC-MCC with skim milk in different proportions. Acidification of the RCM to pH 5.2 increased from 240 min for skim milk (normal concentration of milk) to 270, 290, 300 and 330 min for mixtures containing 25, 50, 75 and 100% HC-MCC. While the increased buffering capacity of the concentrated milks because of higher protein and phosphate levels, there was still adequate lactose present in HC-MCC to support fermentation to pH 5.2. For making cheddar cheese from RCM with setting at 31°C, cutting of set curd after 30 min, cooking of cut curd to 38°C with 95 min set-to-drain time followed by cheddaring with 85 min drain-to-mill time starter culture was added at its normal levels ad 2 and 4 times as much. Prior to cutting, the curd was overlaid with 750 ml of ultrafiltered milk permeate to minimize curd breakage upon stirring. Initially there was rapid moisture loss from curd after cutting, followed by a linear pattern until whey drainage. A faster drop in pH increased whey expulsion from the curd Curd pH at draining was lower with faster acidification, the values being 6.5, 6.4, 6.1 and 5.8 for culture additions of 0.5X, 1X, 2X and 4X respectively. Cheese pH after 14 d of refrigerated storage was likewise affected with pH of 5.4, 5.3, 5.2 and 5.1, respectively. Mean cheese moisture contents were 37.8%, 37.1%, 37.2% and 35.2%, respectively. Cheese moisture and pH were correlated with drain pH. The pH drop that occurs during cheesemaking increases rate and extent of whey expulsion and will produce cheese with lower moisture. To account for the increased buffering capacity of concentrated milk containing 4% casein, a drain pH of 5.9 to 6.0 would be required to obtain a cheese with d 14 pH of ~5.1 instead of the normal drain pH of 6.3. A model cheese making process using 50-mL centrifuge tubes and a mechanical rotator was used to study moisture loss and fat retention in RCM containing 3.5%, 7%, and 10.5% casein with casein to fat (C/F) ratios of 0.60-0.75. Glucono-δ-lactone and rennet proportional to the casein protein level of the RCM were added to provide acidification and coagulation activity, respectively. After cut, curds were agitated using the inverting motion of a tube rotator, and the curds were heated up to 40°C. Whey was drained and collected followed by more agitation. Final whey separation was accomplished by centrifuging of the RCM samples at 250 g for 30 min. Homogenization of 7% casein RCM samples using a microfluidizer prior to cheese making was also investigated to determine if fat retention and curd yield could be improved without increasing curd moisture. Increasing RCM concentration to 10.5% casein increased fat retention to 84.3% compared to 64.4% and 62.0% for RCM with 3.5% and 7.0% casein, respectively. RCM of 10.5% casein also had higher relative dry curd yields, 9.5% versus 8.8% and 7.4% respective to 7.0% and 3.5% casein. Lower moisture was also achieved with increased RCM concentration, with 44.6% for 10.5% RCM compared to 47.9% and 48.5% for 7.0% and 3.5% casein, respectively. Homogenization of RCM increased fat retention from 66.2% at control to 95.0% at 0.41 MPa and increased curd yield from 18.8% at control to 23.2% at 0.41 MPa gauge pressure moisture was lowered from 48.0% to 45.0% (P< 0.01) from control to 0.41 MPa. Homogenization, therefore, has the potential to improve the cheese making performance of RCM without adversely increasing curd moisture levels.
Publications
- Type:
Book Chapters
Status:
Published
Year Published:
2021
Citation:
McMahon, D. J., & Sharma, P. (2021). History of Dairy Processing, Technology and Products. Encyclopedia of Dairy Sciences, 3rd edition. Elsevier
- Type:
Book Chapters
Status:
Published
Year Published:
2021
Citation:
McMahon, D. J., Sharma, P., & Oberg, C. J. (2021). CHEESE: Pasta-Filata Cheeses: Low-Moisture Part-Skim Mozzarella (Pizza Cheese). Encyclopedia of Dairy Sciences, 3rd edition. Elsevier
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Progress 10/01/19 to 09/30/20
Outputs
Target Audience:US cheese manufacturing industry is the target audience, especially those involved in product development and technical services. This group will be reached through presentations at dairy science meetings, cheese technology meetings and annual meeting of Western Dairy Center. Changes/Problems:No new students were involved this year because of COVID restrictions. What opportunities for training and professional development has the project provided?A master student was trained in scientific writing and a thesis was completed: Geslison, R. 2020. Influence of protein concentration and homogenization on moisture content, curd yield, and fat retention of model cheese made from microfiltered skim milk recombined with cream. How have the results been disseminated to communities of interest?No presentations were made this year. What do you plan to do during the next reporting period to accomplish the goals?Prepare a manuscript for publication in the Journal of Dairy Science.
Impacts
What was accomplished under these goals?
The model cheese making system using a rotating system and centrifugation was compared to moisture loss form curd that occurs during manufacture of cheddar cheese. When making cheese from nonconcentrated milk the moisture content is about 87.5%. When using recombined microfiltered concentrated milk (RCM) the moisture content is lower as the solids content is increased. For RCM containing 3.5% casein, 7% casein, and 10.5% casein, the moisture contents were 87.9%, 77.5%, and 67.9%, respectively. Even though the 3.5% casein RCM contained about 35% more casein than normal milk, the moisture contents are similar because the whey proteins have been mostly removed and some of the lactose as well via the microfiltration and diafiltration. In making cheddar cheese, by the time the whey is drained (about 1 h 45 min after adding rennet) the moisture level in the curd has dropped to about 62%. During cheddaring which may take an additional 3 h, whey continues to be expelled and the moisture content of the curd drops to about 43%. Then after salting and pressing the cheese will be about 38%. When using the model process, the process time had been reduced to 2 h and the average moisture was 48.5%, 47.9%, 44.6% curd made from RCM containing 3.5%, 7%, and 10.5% casein, respectively. So while the model system had differences between RCM with different casein levels, the model was not able to achieve the moisture level of cheddar cheese but rather a moisture level comparable to part way through the cheddaring process. When using the model system, curds from RCM expelled moisture faster than in regular cheesemaking but the moisture loss did not continue. Same effect on achieving lower moisture as the protein content of RCM was increased from 3.5 to 10.5% casein. Removing moisture prior to cheesemaking using microfiltration (as for ultrafiltration) compensated for the smaller amount of whey that was expelled. For the curd made from 10.5% casein RCM the final moisture was 44.6%. As expected the yield of curd from RCM increased with concentration level from 14.4% with 3.5% RCM to 36.2% and 55.0% for RCM having 7.0% and 10.5% casein, respectively. When these yields were considered on the fat and protein content of the RCM and the relative concentration factor compared to the 3.5% RCM, there was more fat and protein retained as the concentration level increased. It increased from 7.4% for the lowest level of %casein in RCM to 8.8% and 9.5% at the higher concentrations. This can be explained by less fat and protein being lost into the whey because of less whey expulsion needing to occur during cheesemaking because it had been removed during filtration before cheesemaking.
Publications
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Progress 10/01/18 to 09/30/19
Outputs
Target Audience:US cheese manufacturing industry is the target audience, especially those involved in product development and technical services. This group will be reached through presentations at dairy science meetings, cheese technology meetings and annual meeting of Western Dairy Center. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The student working on developing a model system of cheesemaking for studying cheese making using concentrated milk had obtained employment in the dairy industry and through 2019 worked on completing his MS thesis. How have the results been disseminated to communities of interest?Two presentations were made to cheese industry professionals at the Global Cheese Technology Forum. One presentation was on whey expulsion on concentrated milk in general, the other was on how recombined concentrated milk made from concentrated micellar casein and cream can be used for cheesemaking and its influence on whey expulsion. What do you plan to do during the next reporting period to accomplish the goals?1. Prepare a manuscript for publication in the Journal of Dairy Science based upon the work completed by the 2 MS students who worked on this project. 2. Develop a cheese making process for using concentrated milk.
Impacts
What was accomplished under these goals?
Further work on Objective 4 was completed using a model cheese making process using 50-mL centrifuge tubes and a mechanical rotator .Micellar casein concentrate (from microfiltered (MF) skim milk) was mixed with cream and UF permeate to obtain recombined concentrated milks (RCM) of 3.5%, 7%, and 10.5% casein with casein to fat (C/F) ratios of 0.60-0.75 Glucono-δ-lactone (GDL) and rennet proportional to the casein protein level of the RCM were added to provide acidification and coagulation activity, respectively. After cut, curds were agitated using the inverting motion of a tube rotator, and the curds were heated up to 40°C. Whey was drained and collected followed by more agitation. Final whey separation was accomplished by centrifuging of the RCM samples at 250 g for 30 min. Homogenization of 7% casein RCM samples using a microfluidizer prior to cheese making was also investigated to determine if fat retention and curd yield could be improved without increasing curd moisture. Increasing RCM concentration to 10.5% casein increased (P< 0.05) fat retention to 84.3% compared to 64.4% and 62.0% for RCM with 3.5% and 7.0% casein, respectively. RCM of 10.5% casein also had higher (P< 0.05) relative dry curd yields, 9.5% versus 8.8% and 7.4% respective to 7.0% and 3.5% casein. Lower moisture was also achieved (P< 0.05) with increased RCM concentration, with 44.6% for 10.5% RCM compared to 47.9% and 48.5% for 7.0% and 3.5% casein, respectively. Homogenization of RCM increased (P< 0.001) fat retention from 66.2% at control to 95.0% at 0.41 MPa and increased (P< 0.01) curd yield from 18.8% at control to 23.2% at 0.41 MPa gauge pressure (GP). Moisture was lowered from 48.0% to 45.0% (P< 0.01) from control to 0.41 MPa GP RCM. Homogenization, therefore, has the potential to improve the cheese making performance of RCM without adversely increasing curd moisture levels.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Panthi, R. R., Kelly, A. L., McMahon, D. J., Dai, X., Vollmer, A., & Sheehan, J. J. (2019, June). Response surface methodology modeling of protein concentration, coagulum cut size and set temperature on curd moisture loss kinetics during curd stirring. Journal of Dairy Science, 102(6), 4989-5004
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Ram, P. R., Kelly, A. L., Sheehan, J. J., Bulbul, K., Vollmer, A. H., & McMahon, D. J. (2019, January). Influence of protein concentration and coagulation temperature on rennet-induced gelation characteristics and curd microstructure. Journal of Dairy Science, 102(1), 171-189
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Progress 10/01/17 to 09/30/18
Outputs
Target Audience:US cheese manufacturing industry is the target audience, especially those involved in product development and technical services. This group will be reached through presentations at dairy science meetings, cheese technology meetings and annual meeting of Western Dairy Center. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?A graduate student was trained in cheesemaking and performed trials on whey expulsion and completed an MS thesis. Another graduate student developed a small lab-scale method for comparing whey expulsion from renneted cheese curd. The visiting scholar from the previous year returned to USU for a short time to repeat some trials on whey expulsion. A visiting scientist from Egypt was trained in cheesemaking and performed whey expulsion experiments. How have the results been disseminated to communities of interest?Presentations were made at the annual meeting of the American Dairy Science Association. Research papers were submitted to Journal of Dairy Science related to how protein concentration, curd size and temperature influence whey expulsion of cheese curd. An MS thesis was completed and in available in USU Digital Commons. What do you plan to do during the next reporting period to accomplish the goals?Confirm the cheesemaking protocol that was developed for making cheese with 365 to 38% moisture content and with pH 5.1 to 5.2
Impacts
What was accomplished under these goals?
Objective 4 has been undertaken through studying both milk concentrated by ultrafiltration as a baseline and exploratory study on whey expulsion during cheesemaking, and using recombined concentrated milk made from cream combined with highly concentrated micellar casein concentrate to investigate the effect on whey expulsion on pH change during cheesemaking. Whey expulsion and acidification were studied for making cheddar cheese using milk containing 4 to 9% protein. Pasteurized milk was ultrafiltered to ~3.5X concentration then diluted with permeate to required protein levels. A time-standardized make procedure was prepared based on ~4 to 12 kg of milk such that each mini-vat contained ~400 g of casein. Acidification was by adding ~0.5% of a pH-controlled bulk starter. The milk was renneted and prior to cutting, 1.5 kg of permeate was overlaid upon the curd to minimize curd breakage upon stirring and facilitate curd syneresis. The pH and moisture of curd was monitored during cheesemaking and in the final cheese. Although whey expulsion decreased as protein concentration increased, when combined with the "whey expulsion" via the ultrafiltration process prior to cheesemaking, the curd made from 9% protein milk was lower (P < 0.05) in moisture than curd made from 4% protein milk after cooking and before draining. After cheddaring, milling and salting there was slight but not statistically significant differences in curd moisture. The final cheeses made using higher protein concentrations were about 1% lower in moisture than those made at the lower concentrations (R2 = 0.55). Even though culture was standardized to protein concentration, this did not completely compensate for increased buffering capacity of the curd and there was less pH drop during cheesemaking as protein level increased: with differences of 0.1 units prior to draining and 0.2 units prior to pressing, such that the pH after 1 d increased from pH 4.9 to pH 5.1 for cheese made from 4% and 9% protein milk, respectively. During 30-d of storage the pH of the cheese increased ~0.2 units. In conclusion, provided the starter activity added is increased to match the protein concentration, and permeate is added to help float the curd upon cutting, cheddar cheese can be manufactured within moisture and pH targets with milk containing up to 9% protein. To understand whey expulsion kinetics during cheese making it is also necessary to understand the affects curd cut size and temperature as well as changes in protein content. This was studied with protein concentration (4 to 6%), coagulum cut size (6 to 18 mm3), and coagulation temperature (28 to 36°C). Milk (14 kg) in a cheese vat was rennet-coagulated, cut, and stirred as per semi-hard cheesemaking conditions. During stirring, the moisture content of curd samples was determined every 10 min between 5 to 115 min after cutting. The moisture loss kinetics of curds cut to 6 mm3 followed a logarithmic trend, but the moisture loss of curds from larger cut sizes, 12 or 18 mm3, showed a linear trend. Curd moisture was positively correlated with cut size and negatively correlated with milk protein level. Initial set temperature had a negative effect on initial rate of whey expulsion but this difference was overcome by whey expulsion during and after cooking. A problem as the protein content of the milk is increased (e.g., to 5-6%) is increased breakage of the larger curd particles during initial stirring. This was remedied by overlaying the curd with UF permeate prior to cutting and stirring the curd. This study was performed with pH of the curd changing little prior to draining the whey. Our next study was to determine the extent to which pH drop prior to draining of whey influences cheese curd syneresis, cheese curd moisture before draining, and final cheese moisture when using recombined concentrated milk. Recombined milk (7.5 kg) was prepared by mixing micellar casein concentrate (~9% casein), cream, and skim milk to 4% casein and casein-to-fat ratio of 0.68. Four levels (0.5 times (X), 1X, 2X and 4X)) of a pH-controlled bulk starter culture were used to obtain different rates of pH change during cheesemaking where X is the normal amount of culture (0.5%) used in cheesemaking. Cheesemaking involved a typical cheddar make procedure with setting of prepared milk at 31°C, cutting of set curd after 30 min, cooking of cut curd to 38°C with 95 min set-to-drain time followed by cheddaring with 85 min drain-to-mill time. Prior to cutting, the curd was overlaid with 750 ml of ultrafiltered milk permeate to minimize curd breakage upon stirring. Initially there was rapid moisture loss from curd after cutting, followed by a linear pattern (R2 > 0.95) until whey drainage. A faster drop in pH increased whey expulsion from the curd (p = 0.0002). With initial curd moisture levels at 5 min of 83.7% and 83.3% using 0.5X and 4X culture, respectively, curd moisture level of 75.0% and 72.8% respectively were obtained at 50 min (during cooking), and 65.5% and 58.5% respectively, at 95 min (at draining). As cheese make times were fixed, curd pH at draining was lower with faster acidification, the values being 6.5, 6.4, 6.1 and 5.8 for culture additions of 0.5X, 1X, 2X and 4X respectively. Cheese pH after 14 d of refrigerated storage was likewise affected with pH of 5.4, 5.3, 5.2 and 5.1, respectively. Mean cheese moisture contents were 37.8%, 37.1%, 37.2% and 35.2%, respectively. Cheese moisture and pH were correlated with drain pH (R2 = 0.48 and 0.71, respectively). To conclude, the pH drop that occurs during cheesemaking increases rate and extent of whey expulsion and will produce cheese with lower moisture. To account for the increased buffering capacity of concentrated milk containing 4% casein, a drain pH of 5.9 to 6.0 would be required to obtain a cheese with d 14 pH of ~5.1.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2018
Citation:
Presentations
Motawaee, M. M. (Presenter & Author), McMahon, D. J. (Author Only), American Dairy Science Association Annual Meeting, "Influence of increasing milk protein concentration from 4 to 9% using ultrafiltration on Cheddar cheese pH and moisture," American Dairy Science Association, Knoxville, TN. (June 25, 2018)
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2018
Citation:
Presentations
Bulbul, K. (Presenter & Author), McMahon, D. J., American Dairy Science Association Annual Meeting, "Influence of pH on whey expulsion from curd made from recombined concentrated milk.," American Dairy Science Association, Knoxville, TN. (June 25, 2018)
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Progress 10/01/16 to 09/30/17
Outputs
Target Audience:US cheese manufacturing industry is the target audience, especially those involved in product development and technical services. This group will be reached through presentations at dairy science meetings, cheese technology meetings and annual meeting of Western Dairy Center. Changes/Problems:No change in plan of work. What opportunities for training and professional development has the project provided?Two graduate student were trained in measurement of rheological gelation properties of concentrated milks. A visiting student performed cheesemaking and increased skills as part of a PhD program. How have the results been disseminated to communities of interest?A presentation was made at the Global Cheese Technology Forum to professionals in the cheese industry. Presentations were made to interested dairy foods industry technical staff as part of the BUILD Dairy program of the Western Dairy Center. What do you plan to do during the next reporting period to accomplish the goals?Further work on the effect of casein level on whey expulsion during cheesemaking will be performed.
Impacts
What was accomplished under these goals?
Objective 2 has been completed. Understanding rennet gelation of RCM and its rheological properties can help in designing process systems for using RCM for cheesemaking. HC-MCC was mixed with cream using low shear at 50°C for 10 min, followed by cooling to 31, 28, or 25°C to form RCM. By adding rennet, the rheological properties of RCM were determined. Rennet coagulation time (RCT, the time at which storage modulus (G') decreased from 8.7 to 7.4 min as casein level increased from 3.2 to 5.7%, without a significant additional difference in RCT at casein levels > 5.7%. The initial loss modulus increased about 10 fold when casein levels were increased from 3.2 to 10.9%, whereas no change in initial G' was observed. When G' was measured relative to RCT (i.e., 1, 1.5 or 2 times RCT after RCT was reached there was a log relationship between relative G' and casein level (R2 > 0.94). Lowering coagulation temperature from 31 to 25°C increased initial loss modulus by 6 fold and extended RCT from 7.4 to 9.5 min. After coagulation, relative G' was initially higher at the lower temperature with G'1 of 3.6 Pa at 25°C and 2.0 Pa at 31°C, but delayed in further development. Lowering pH of RCM from 6.6 to 6.2 resulted in reduced RCT from 11.9 to 6.5 min with increased relative G' after coagulation. When less rennet was used, RCT increased in a linear inverse relationship without changes in relative G' or G''. The microstructure of RCM coagulum (~11% casein) observed using transmission electron microscopy, confirmed that RCM curd had a rigid protein matrix containing extensively cross-linked protein strands. Understanding rennet coagulation of RCM is necessary for designing processing systems when RCM is used in cheese making. Reducing renneting level can lengthen coagulation time of RCM but it does not affect curd firmness or firming rate. Decreased coagulation temperature can lengthen coagulation time and slow curd firming rate, but it also increases initial viscosity of RCM, which might result in the requirement of specialized equipment to handle a RCM with four times the normal casein level. The viscosity of RCM is less of a problem at lower concentrations, but even at twice the normal casein level there is a noticeable increase in loss modulus. Concentrating milk by microfiltration has similar effects on RCT as does ultrafiltration, with no differences in RCT observed for milk containing ≥5.7% casein. While RCT remains similar, the firming rate does increase with casein concentration and the curd has G' values l00-fold of more higher than is typical for curd made by renneting milk. When pH of RCM was lowered to pH 6.2 prior to renneting, coagulation was accelerated as well as the rate at which curd firming occurred when measured relative to RCT. Analysis of microstructure of RCM and its coagulum confirmed that the increased curd firmness probably results from a stronger protein matrix formed by highly inter-linked protein strands in RCM curd. Overall, RCM with a casein level of 11 to 12% has potential for use in cheese making provided its higher viscosity compared to milk and its fast curd firming rate can be overcome. Thus, the same problems exist for high casein milks made using microfiltration as those already known for milk concentrated using ultrafiltration. Objective 3 has been completed with acidification of RCM at different casein concentrations why mixing HC-MCC with skim milk in different proportions. Acidification of the RCM to pH 5.2 increased from 240 min for skim milk (normal concentration of milk) to 270, 290, 300 and 330 min for mixtures containing 25, 50, 75 and 100% HC-MCC. While the increased buffering capacity of the concentrated milks because of higher protein and phosphate levels, there was still adequate lactose present in HC-MCC to support fermentation to pH 5.2. An initial study of the effect of protein concentration on whey expulsion during cheesemaking was performed using milk concentrated by ultrafiltration. At 36°C there is faster initial whey expulsion and moisture loss in curd compared to curd set at 32 or 28°C. However, during cooking to 37°C curd formed at the lower temperatures undergoes a greater increases in temperature and more whey is expelled during cooking. Protein concentration influenced moisture content of the curd and to obtain curd with similar moisture content, if the initial milk concentration is increased from 4 to ~5.5% protein, the curd needs to be cut at a larger size to compensate for the initial difference in moisture content of the milk even though the rate constant for whey expulsion decreases slightly as protein concentration increases.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Lu, Y., McMahon, D. J., Vollmer, A. (2017). Investigating rennet coagulation properties of recombined highly concentrated micellar casein concentrate and cream for use in cheese making. J. Dairy Sci., 5132-5143.
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Progress 03/29/16 to 09/30/16
Outputs
Target Audience:Target Audience US cheese manufacturing industry is the target audience, especially those involved in product development and technical services. This group will be reached through presentations at dairy science meetings, cheese technology meetings and annual meeting of Western Dairy Center. Changes/Problems:Changes/Problems No changes to proposed research. What opportunities for training and professional development has the project provided?Opportunities A graduate student was trained in gelation properties of concentrated milks. How have the results been disseminated to communities of interest?Dissemination Presentations were made at the annual meeting of the American Dairy Science Association to students, and professionals from academia and the dairy foods industry. Presentations were made to interested dairy foods industry technical staff as part of the BUILD Dairy program of the Western Dairy Center. What do you plan to do during the next reporting period to accomplish the goals?Plan of Work Work on rennet coagulation and acidification of recombined concentrated milk will be performed.
Impacts
What was accomplished under these goals?
Accomplishments Objective 1 was completed. Understanding cold gelation of RCM and its rheological properties can help in designing process systems for using RCM as an ingredient in food applications. At pH 6.6, an RCM with 12% casein does not gel until cooled below 12°C and so would not interfere with cheese making. If the pH is higher than 6.6, then gelation occurs at higher temperatures unless the casein concentration is lowered. For example, at pH 7.0 RCM with 12% casein gels at 37°C. Based upon the relationship between pH and cold gelation temperature it was predicted that RCM with 12% casein would not gel even when cooled to 5°C. Addition of either sodium citrate or high levels of calcium (i.e., ≥ 0.17 mmol/g casein) increased CGT, although low levels of calcium (i.e., ≤ 0.12 mmol/g casein) did not impact CGT. Cold gelation of RCM was thermally reversible, even when citrate was added to partially chelate calcium. Compared to cold-gelled HC-MCC, the cold-gelled RCM, the casein micelles were less closely packed together and appeared as being partially dissociated. We propose that cold gelation of RCM occurs when protein strands that have been partially released from the casein micelles entangle, restrict their mobility and form a fine stranded gel network. Such a network consists of these fine strands of proteins as well as the modified casein micelles. In general, lowering temperature, increasing pH above 6.6, or adding chelating calcium accelerates dissociation of casein micelles. Formation of a gel network that is dependent upon entanglement of protein strands that are only loosely-associated with the casein micelles would be favored when there is increased dissociation of casein micelles. When high levels (21 mmol/g casein) of calcium are added to RCM, the casein micelles were less dissociated but gelation was promoted, presumably through direct aggregation of casein micelles. Provided pH of RCM is not above the normal pH of milk, RCM at a casein level of 12% (wt/wt) has potential for use in cheese making.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Publications
Lu, Y., McMahon, D. J., Vollmer, A. (2016). Investigating cold gelation properties of recombined highly concentrated micellar casein concentrate and cream for use in cheese making. J. Dairy Sci., 99(7), 5132-5143.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Presentations
Ying, L. (Presenter & Author), McMahon, D. J. (Author Only), Vollmer, A. (Author Only), Joint Annual Meeting, "Gelation properties of micellar casein concentrate when recombined with cream," American Dairy Science Association, Salt Lake City, UT. (July 19, 2016 - July 22, 2016)
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