Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: As part of the vatless cheese manufacture process, virgin whey (VW) is harvested as permeate from the microfiltration (MF) of slightly acidified (pH 6.0) skim milk before cheesemaking. It does not contain cheesemaking remnants typical of commercial whey. Not subjected to extreme physicochemical changes during cheesemaking and pretreatment prior to concentration process, VW proteins are in their native conformation. However, being in a dilute stream, the protein content is increases by ultrfiltration (UF) before drying into powder. Development of an appropriate mathematical model for process design and effective prediction of fouling behavior of VW during UF processing was thus undertaken. The research work and results have been presented at several technical meetings organized by professional society like the Institute of Food Technologists and American Dairy Science Association. Several potential users interested in the process have been updated with the latest research findings and derivative process and products have also been identified for further investigations. PARTICIPANTS: Syed Rizvi, PI. Philipina Marcelo, Graduate student. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
A mathematical model that describes flux decline in the ultrafltration (UF) of virgin whey (VW) was derived from one of the flux models used in the UF of cheese whey. The present model was based on the hypothesis that since VW is free of cheesemaking remnants, richer in native whey proteins compared with cheese whey, and that its composition is constant, its long-term UF fouling behavior will be consistent at a given set of operating parameters. Both the short-term flux decline and average flux will depend primarily on the ratio of total UF feed (F) to membrane area (A). The derived equation consisted of two fouling parameters: F/A, which quantifies short-term fouling, and m, which quantifies long-term fouling. Different amounts of VW were concentrated 13 times using polysulfone membrane in spiral wound configuration (10,000 molecular weight cut-off) at 45C, 338 kPa transmembrane pressure, and 0.5 m s-1 crossflow velocity. Results confirmed that long-term fouling behavior is consistent as shown by a constant m value, while the average flux changes significantly with the F/A value. The present flux equation does not only aid in understanding VW fouling behavior but may also be used as design equation for UF system optimization.
Publications
- Marcelo, P. A. and Rizvi, S.S.H. 2008. Physicochemical properties of liquid virgin whey protein isolate. Int'l Dairy Journal 18(3):236-246.
- Marcello, P.A. and Rizvi, S.S.H. 2008. Mathematical modeling of batch ultrafiltration of virgin whey. Institute of Food Technologists Annual Meeting, June 28-July 01, New Orleans, Book of Abstracts, No. 207-01.
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Progress 10/01/06 to 09/30/07
Outputs
Whey proteins obtained as a byproduct stream during the manufacture of Mozzarella cheese from concentrated microfiltration retentate continue to be of specific interest because of their superior nutritional profile. Harvested before cheesemaking by microfiltration (MF) and concentrated by ultrafiltration (UF), the native protein-rich liquid virgin whey protein isolate (LVWPI) also offers unique physicochemical properties. Whether these properties translate to unique functional behavior was further investigated. Using differential scanning calorimetry (DSC), the thermal properties of LVWPI were determined while its aggregation and gelation behavior was investigated using viscometry, rheology, particle size analysis (PSA) and confocal laser scanning microscopy (CLSM). The results were compared with those of commercial whey protein (WP) products. LVWPI was found to be more thermostable as shown by 11-25 percent higher enthalpy of denaturation compared to whey protein
isolate (WPI) and concentrate (WPC-80) manufactured from conventional cheese whey by MF and UF. At 8 percent (w/w) protein concentration, while WPI solution viscosity increased rapidly after 10 min of heating at 70C, the LVWPI's viscosity was constant for 90 min. PSA showed that it takes 1 h at 80 C for LVWPI aggregates to grow to the same size as WPI aggregates formed after 10 min of heating at 70 C. When heated at 80 C for 10 min, both WPI and WPC-80 solutions turned to gel while LVWPI took 3 h to turn to weak gel. Containing half as much Ca as MF-UF WPI made from cheese whey, the addition of 5 mM calcium chloride increased the storage modulus of LVWPI gel to equal that of WPI gel without calcium chloride while 10 mM CaCl2 increased its storage modulus to equal that of ion-exchange (IE) WPI gel with 10 mM calcium chloride.
Impacts
The unique features observed in the native protein-rich liquid virgin whey protein isolate (LVWPI) should permit fine-tuned heat-induced texture development in products by mineral modulation alone. Confocal laser scanning microscopy images showed that LVWPI gels were made of strands that were thicker than those found in ion exchange WPI gel and aggregates that were smaller in size than those found in the MF-UF WPI gel. These findings exhibited LVWPI's potentials in developing wide range of texture qualities in food products where nutrition is important.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
Whey proteins (WP) continue to be important to the food ingredients industry. Harvested before cheese making and concentrated by ultrafiltration (UF) alone, the liquid virgin whey protein isolate (LVWPI) has unique physicochemical properties not observed in commercial products. We studied the functional behavior, microstructure formation and texture development under heat and shear applications of LVWPI and compared with commercial products. VW was harvested from slightly acidified skim milk prior to cheese making using a Megaloop microfiltration system. The VW at pH 6.0 was then concentrated in a two-stage UF system with diafiltration (DF) at 45 C. The first-stage UF was carried out in a polysulfone (PSf) spiral wound membrane, with a molecular weight cut-off (MWCO) of 10 kDa and the second-stage UF was done using PSf hollow fiber membrane. The thermal properties of LVWPI and the commercial WP products were determined by differential scanning calorimetry.
Textural changes during heat and shear applications were quantified by rheological measurements and particle size analyses. Structure development was elucidated by confocal laser scanning microscopy (CLSM). The peak of WP denaturation was observed to be similar to those of commercial products but LVWPI's onset and enthalpy of denaturation were higher, indicating higher thermal stability. The apparent viscosity at pH 6.0 of 8% LVWPI at 70C and 245 per second shear rate was constant for about 90 minutes before increasing at a steady rate of about 0.9 mPa-s per minute to 27 mPa-s while those of commercial products increased rapidly at 0.25 mPa-s per minute from the start of the test. CLSM results indicated well-controlled structure development of LVWPI upon heating, producing fine-stranded gel similar to commercial LVWPI produced from ion-exchange. These results suggest that LVWPI is ideally suited for imparting fine-tuned texture in foods compared with existing commercial WP
products.
Impacts
The functional properties of the liquid virgin whey protein isolate (LVWPI) were found to be unique and not observed in commercial products. This provides an alterate startegy for harvesting whey protein for use as ingredients in food formulations.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
Whey proteins (WP) produced during cheesemaking continue to be important to the food ingredients industry due to incessant demand for products of specific texture and nutritive value. However, the compositional variability and fractional protein denaturation in commercial WP products give rise to varied levels of aggregation during heat and shear applications. This often results in uncontrolled structure development and impedes attainment of the desired texture. The liquid virgin whey protein concentrate (LVWPC) is a novel ingredient rich in native WP. Harvested before cheesemaking and concentrated by membrane technology alone, LVWPC offers unique physicochemical properties not observed in commercial products. We have studied the behavior of LVWPC, microstructure formation and texture development under heat and shear applications and compared them with those of commercial products. While the peak of denaturation was similar to those of commercial products, the onset
and enthalpy of denaturation of LVWPC were higher, indicating higher thermal stability. The apparent viscosity at pH 6.1 of 8 percent LVWPC at 70C and 245 per second shear rate was constant for a period of time before increasing at a steady rate of 0.18 mPa-s per minute to 27 mPa-s while those of commercial products increased rapidly at 0.25 mPa-s per minute from the start of the test. SEM images showed that the sheared and heat-treated LVWPC formed a continuous structure, giving smooth texture, while the commercial products gave fractured or flaky texture due to extensive aggregation that led to phase separation. Confocal laser scanning microscopy results indicated well-controlled structure development of LVWPC upon heating.
Impacts
Recovery of whey proteins in their most native state is achieved by harvesting them via microfiltration of milk prior to cheesemaking. This approach, coupled with cotinuous cheesemaking using the retentate, offers the most direct benefits to the cheesemakers and consumers.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
Accurate determination of curd cutting time is essential for quality control and for planning the operational protocol during cheese making. A soft coagulum causes loss of milk solids in the whey whereas a coagulum that is too hard results in poor product quality. In this study, the storage modulus and tan delta of retentate-based microfiltration cheesemilk (MCM) were measured as a function of time and related to the rate and extent of kappa-casein hydrolysis. Pasteurized skim milk was microfiltered to 6, 7 and 8 times its original weight at 50C and pH 6.0 using 0.1-mm ceramic membranes. A control cheesemilk (CCM) was prepared with the same casein to fat ratio as the MCM. The rennet to casein ratio was kept constant for all cheesemilk samples. The hydrolysis of kappa-casein was found to follow a first order reaction kinetics. The reaction rate constants were 2.70(10-3) s-1, 1.80(10-3) s-1, 1.45(10-3) s-1, and 1.20(10-3) s-1 for the CCM and 6X-, 7X-, and 8X-MCM,
respectively, which indicated that hydrolysis, was slower in the concentrated milk than in the CCM. Rheological measurements showed that the rate of firmness of the coagulum was 1.8 times higher in the 8x-MCM, while the rate of kappa-casein hydrolysis was 2.25 times lower than in the CCM. An equation was developed to predict the appropriate curd cutting time (CCT) for cheesemilk of various concentration factors. The CCT, defined as the time required for 95 pct kappa-casein hydrolysis, was 35.9 minutes for the 8X-MCM and 18.5 minutes for the CCM.
Impacts
The kinetics of coagulation of microfiltration concentrated milk was found to be critical for producing good quality cheese curd and has been quantified. Based on this approach, a new process and protocols have been developed for cheese manufacture from highly 8-10 X concentrated retentate obtained by microfiltration with 0.2-micron membranes of acidified skim milk to reduce Ca and WP levels. This overall approach to retentate cheesemaking has the potential to produce cheese with normal Ca levels but with significantly reduced amounts of WP as compared to UF cheese. A continuous process would also lead to considerable savings in manufacturing costs.
Publications
- Ardisson-Korat A. V. and Rizvi, S. S. H. 2004. Vatless manufacturing of low-moisture part-skim Mozzarella cheese from highly concentrated skim milk microfiltration retentates. J. Dairy Sci. 87:3601-3613.
- Ardisson, A.V. and Rizvi, S.S.H. and Moraru, C.M. 2004. Rennet coagulation behavior of highly concentrated cheese milk obtained by microfiltration. 2004 Institute of Food Technologists Annual Meeting, July 12-16, Las Vegas, Book of Abstracts, p107 (abs. 46-10).
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Progress 01/01/03 to 12/31/03
Outputs
A continuous process for low-moisture part-skim (LMPS) Mozzarella cheese manufacture using retentates (concentration factor up to 9 X) from crossflow microfiltration (CFMF) was attempted. It utilized a continuous microfiltarion unit and a semi-continuous curd making system, operating in tandem. The final cheese had the same compositional characteristics as its commercial counterpart. A batch cooking and then a continuous stretching step followed this. The use of GDL during microfiltration of skim milk achieved a pH 6.0 in the final retentate which produced a Ca:casein ratio in the range found in commercial LMPS Mozzarella cheese. The functional characteristics (stretchability and meltability) of the MF cheeses made showed differences when compared to commercial products. This is likely caused by reduced secondary proteolysis due to the absence of starter culture. Considering prior research and the results from this study the addition of starter cultures is probably
required to increase the secondary proteolysis levels and improve the functional characteristics of the MF LMPS Mozzarella cheese. Additional advantages of the process include reduced rennet utilization (85.9 percent), reduced size of cheese making operation and about 66 - 71 percent depletion of whey proteins in the retentate.
Impacts
Removal of whey proteins from milk prior to cheese making by microfiltration offers a promising new strategy to reduce the cost of cheese production and to recover virgin whey proteins of superior functional properties. Based on this approach, a new process and protocols have been developed for cheese manufacture from highly 8-10 X concentrated retentate obtained by microfiltration with 0.2-micron membranes of acidified skim milk to reduce Ca and WP levels. This overall approach to retentate cheesemaking has the potential to produce cheese with normal Ca levels but with significantly reduced amounts of WP as compared to UF cheese. A continuous process would also lead to considerable savings in manufacturing costs.
Publications
- Brandsma, R. and Rizvi, S.S.H. 2001. Effect of manufacturing treatment on the rheological characteristics of Mozzarella cheese made from microfiltration retentate depleted of whey proteins. Int'l J. Food Sci. Technol. 36(6):601-610.
- Brandsma, R. and Rizvi, S.S.H. 2001. Manufacture of Mozzarella cheese from highly concentrated skim milk microfiltration retentate depleted of whey proteins. Int'l J. Food Sci. Technol. 36(6):611-624.
- Vadi, P.K. and Rizvi, S.S.H., 2001. Experimental evaluation of a uniform transmembrane pressure crossflow microfiltration unit for the concentration of micellar casein from skim milk. J. Mem. Sci. 48(8):1-14.
- Ardisson, A.V. and Rizvi, S.S.H. 2003. Continuous manufacture of Mozzarella cheese using concentrated microfiltration retentate and recovery of virgin whey proteins. J. Dairy Sci. 86:368.
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Progress 01/01/02 to 12/31/02
Outputs
Low moisture part skim (LMPS) Mozzarella cheese was manufactured using retentates (concentration factor 10 X) from crossflow microfiltration (CFMF) obtained by two crossflow velocities (CFV) of 6.3 and 5.3 ms-1at pH 6.0 and temperature 50 oC. Cheesemilk was acidified to cheese pH by glucono-d-lactone (GDL) and starter cultures and cheese composition & functionality properties (expressible water, proteolysis, melting and stretching properties) were evaluated at refrigerated storage (4oC) at 1, 7, 14, 21, 30, and 60 days. Cheeses obtained had near similar gross chemical composition and met standards for mozzarella cheese. Proteolysis was quantified by determining pH 4.6 soluble nitrogen and 12 percent TCA (tri-chloroacetic acid) soluble nitrogen. CFV didn't show any significant effect on cheese composition and functionality but type of acidulant (GDL or Starter) affected the proteolysis and expressible serum over extended refrigerated storage. Expressible moisture was
observed to be same as commercial cheese but it took longer for expressible serum to reach to zero, which was longer in cheeses made with GDL. Total moisture remained constant over storage time for all cheeses. The 12 percent soluble TCA and pH 4.6 soluble nitrogen were also observed to be increasing with time, which were also, more in cheese made from starter cultures indicating absence of secondary proteolysis in cheese made with GDL. Meltability of cheese increased with time, more in starter-based cheese while stretchability was similar in both the cheeses but over prolonged storage GDL cheese had higher stretch compared to starter cheese. Efforts are underway to design a continuous cheesemaking process using the above MF retentate.
Impacts
The new approach to taking out whey proteins from milk prior to cheese making by microfiltration offers a promising new strategy to reduce the cost of cheese production as well as recovery of virgin whey proteins of superior functional properties. Based on this approach, a new process and protocols have been developed for cheese manufacture from highly 8-10 X concentrated retentate obtained by microfiltration of acidified skim milk with 0.2-micron membranes to reduce Ca and WP levels. This overall approach to retentate cheesemaking has potential to produce cheese with normal Ca levels with significantly reduced amounts of WP as compared to UF cheese.
Publications
- Brandsma, R.L. and S.S.H. Rizvi. 1999. Depletion of Whey Proteins and Calcium by Microfiltration of Acidified Skim Milk prior to Cheesemaking. Journal of Dairy Science 82 (10) 2063-2069.
- Jost, R., R. L. Brandsma and S. S. H. Rizvi. 1999. Protein composition of micellar casein obtained by cross-flow microfiltration of skimmed milk. International Dairy Journal 9 (3-6) 389-390.
- Solanki, G. and Rizvi, S.S.H. 2001. Physico-chemical properties of skim milk retentates from microfiltration. J. Dairy Sci. 84:2381-2391.
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Progress 01/01/01 to 12/31/01
Outputs
A new cheese-making process was developed which utilizes concentration factor (CF) 8, pH 6.0 skim milk microfiltration (MF) retentate to produce low-moisture, part-skim (LMPS) Mozzarella cheese. The compositional and proteolytic effects of different levels of rennet concentration, coagulation temperature, and post-coagulation curd cutting time were evaluated, with rennet concentration having the strongest influence. A post-coagulation curd cutting time of 15-20 min was found to normalize the extent of casein hydrolysis during coagulation of concentrated MF retentate. Optimal cheese manufacturing parameters were determined to be 80-100 micro liter rennet per kg MF cheesemilk, coagulation temperature of 32-36C, and post-coagulation curd cutting time of 15 min. Lubricated squeezing flow, stress relaxation, melt and stretch measurements demonstrated that commercial LMPS Mozzarella had substantial textural and functional change between 7 and 30 days of age, while the
rheological and functional behaviour of LMPS MF Mozzarella (MFM) exhibited substantial change between 30 and 60 days of age. As compared with ultrafiltration (UF) retentate cheese manufacture, cheese made from MF retentates has potential for improved textural and functional qualities, along with recovery of highly functional whey proteins (WP) from permeate.
Impacts
A new process and protocols have been developed for cheese manufacture from highly concentrated retentate obtained by microfiltration of acidified skim milk with 0.2-micron membranes to reduce Ca and WP levels. This overall approach to retentate cheesemaking has potential to produce cheese with normal Ca levels with significantly reduced amounts of WP as compared to UF cheese. It also permits generation of permeate that has consistent composition, is sterile and extremely low in fat, and contains the major WP in a highly functional state.
Publications
- Brandsma, R. and Rizvi, S.S.H. 2001. Effect of manufacturing treatment on the rheological characteristics of Mozzarella cheese made from microfiltration retentate depleted of whey proteins. Int'l J. Food Sci. Technol. 36 (6): 601-610
- Brandsma, R. and Rizvi, S.S.H. 2001. Manufacture of Mozzarella cheese from highly concentrated skim milk microfiltration retentate depleted of whey proteins. Int'l J. Food Sci. Technol. 36 (6): 611-624.
- Vadi, P.K. and Rizvi, S.S.H., 2001. Experimental evaluation of a uniform transmembrane pressure crossflow microfiltration unit for the concentration of micellar casein from skim milk. J. Mem. Sci. 48(8): 1-14.
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Progress 01/01/00 to 12/31/00
Outputs
The existing microfiltration system was further upgraded to provide a total filtration area of 1.12 m2 from 0.4 m2 (0.2 mm Membralox, US Filter Corp.).This upgrade was made possible due to a generous donation of equipment from U.S. Filter Corp. which permitted concentration of skim milk to 8-9X and even higher concentration factors up to 12 X, in shorter operating time. Microfiltration was conducted with in-process acidification of retentate to pH 6.6, 6.3, and 6.0 for determination of compositional parameters of concentration factor (CF) 8-9 retentate and to quantify the retention and permeation of whey proteins and Ca at each pH level. Cheesemilk made from retentate and butteroil /heavy cream was evaluated for suitability in the manufacture of Mozzarella cheese. Preliminary trials were conducted to optimize microfiltration concentration process by various combinations of uniform - transmembrane pressures and cross-flow velocities, with in-line pH adjustment to 6.5
and 6.0 by glucono-d-lactone (GDL) addition, in order to allow greater separation of caseins and whey proteins and also to achieve a higher CF with lower calcium content in shorter time period. No casein was detected in the permeate stream while 55 and 60 weight % whey proteins were transferred in the permeate stream at pH 6.0 and 6.5, respectively. It is hypothesized that further optimization studies on operational variables would provide conditions for enhanced expulsion of whey proteins and concentrates of higher total solids. A cheesemaking process was developed using CF 8-9, pH 6.0 MF retentate and butteroil / heavy cream. Cheese manufacturing treatments of rennet addition rate, coagulation temperature, and post-coagulation curd cutting time were evaluated for effects on cheesemaking parameters, cheese and whey composition, and proteolytic indices. LMPS MF Mozzarella cheeses were produced using both GDL and starter culture for acidity development and to determine extent and depth
of proteolysis arising from both rennet and starter culture proteases. Concentration factor of 10X and higher was achieved with the upgraded MF system. Preliminary trials were conducted on the manufacture of Mozzarella cheese from 10X MF retentate with little or no whey drainage and to optimize starter culture addition rates with adjustment of rod: coccus ratios for achievement of proteolysis similar to that of commercial LMPS Mozzarella cheese. Cheeses made under objective 2 were evaluated for functional properties of meltability and stretchability, in addition to fundamental rheological measurements of lubricated squeezing flow and stress relaxation in order to quantify effects of manufacturing treatments and to identify areas for improvement in terms of cheese composition and proteolysis. Cheeses were tested for softening point by a new method developed using a dynamic mechanical analyzer. Studies to examine the textural and functional differences in cheeses produced using
combinations of GDL and starter culture are in progress.
Impacts
Microfiltration of acidified skim milk with 0.2 micron m membranes to reduce Ca and WP levels can be used to produce a very suitable, concentrated retentate for use in cheese manufacture. This overall approach to retentate cheesemaking has potential to produce cheese with normal Ca levels with significantly reduced amounts of WP as compared to UF cheese. It also permits generation of permeate that has consistent composition, is sterile and extremely low in fat, and contains the major WP in a highly functional state.
Publications
- Brandsma, R.L. and S.S.H. Rizvi. 1999. Depletion of Whey Proteins and Calcium by Microfiltration of Acidified Skim Milk prior to Cheesemaking. Journal of Dairy Science 82 (10) 2063-2069.
- Jost, R., R. L. Brandsma and S. S. H. Rizvi. 1999. Protein composition of micellar casein obtained by cross-flow microfiltration of skimmed milk. International Dairy Journal 9 (3-6) 389-390.
- Brandsma, R.L. and S.S.H. Rizvi. 2000. Manufacture of Mozzarella cheese from Highly-concentrated Skim Milk Microfiltration Retentate. Int'l Journal of Food Science and Technology (in review).
- Brandsma, R.L. and S.S.H. Rizvi. 1999. Effect of manufacturing treatments on the rheological character of Mozzarella cheese made from microfiltration retentate depleted of whey proteins. Int'l Journal of Food Science and Technology (in review).
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Progress 01/01/99 to 12/31/99
Outputs
A cheesemaking process was developed utilizing pH 6.0, concentration factor (CF) 8-9 microfiltration (MF) retentate and butteroil for production of MF Mozzarella cheese. The aim was to evaluate rennet concentration, coagulation temperature, and post-coagulation curd cutting time for compositional and rheological effects on cheese, with comparisons of MF Mozzarella made using glucono-delta-lactone (GDL) or starter culture. Skim milk MF (0.2 mm) produced CF 8-9 retentate containing 45.6 percent of whey proteins and 62.4 percent of Ca originally in the feed. A response surface design was employed with 15 treatment combinations in which retentate and butteroil were homogenized and acidified using GDL at 32, 36, or 40C, with rennet added at 20, 80, or 140 ml/kg cheesemilk. Curd was cut 10, 15, or 20 min post-coagulation followed by heating and stretching. MF Mozzarella was also made in triplicate at treatment midpoints using 2% starter culture. Cheeses were not
compositionally different and met legal standards for LMPS Mozzarella. Cheeses were not compositionally different by treatment, although significant differences were present in coagulation time and pH 4.6 soluble N due to rennet concentration. use of starter culture adjuncts accelerated proteolysis. When compositions differed significantly, primarily by rennet concentration and curd cutting time. The optimal combination of manufacturing treatments were rennet concentration of 80-100 ul/kg cheesemilk, coagulation temperature of 32-36 C, and post-coagulation curd cutting time of 15 minutes. Rheological parameters of lubricated squeezing flow and stress relaxation were measured as was cheese meltability and stretchability. Cheeses became significantly less elastic and more flowable over time with increasing rennet concentration and with use of starter culture. MFM rheological change was delayed versus control LMPS Mozzarella and was attributable to partial inhibition of rennet and milk
plasmin by remaining WP, lack of starter culture proteases, and cheesemilk homogenization. The developed manufacturing process, along with increased concentrations of residual rennet and use of starter culture, can normalize proteolysis and improve rheological and functional development of MF Mozzarella cheese.
Impacts
(N/A)
Publications
- Brandsma, R. and Rizvi, S.S.H. 1999. Depletion of whey proteins and calcium of microfiltration of acidified skim milk prior to cheese making. J. Dairy Sci. 82:2063-2069.
- Brandsma, R.L. and Rizvi, S.S.H. 1998. Manufacturing of mozzarella cheese from highly-concentrated microfiltration retentate. J. Animal Sci. 76(1):15 (abs. 55).
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Progress 01/01/98 to 12/31/98
Outputs
A cheesemaking process was developed utilizing pH 6.0, concentration factor (CF) 8-9 microfiltration (MF) retentate and butteroil for production of MF Mozzarella cheese. Objectives of this research were to evaluate rennet concentration (Conc), coagulation temperature (Temp), and post-coagulation curd cutting time (Time) for compositional and rheological effects on cheese, with comparisons of MF Mozzarella made using glucono-delta-lactone (GDL) or starter culture. Skim milk MF (0.2 mm) produced CF 8-9 retentate containing 45.6 percent of whey proteins and 62.4 percent of Ca originally in the feed. A response surface design was employed with 15 treatment combinations in which retentate and butteroil were homogenized and acidified using GDL at 32, 36, or 40C, with rennet added at 20, 80, or 140 ml/kg cheesemilk. Curd was cut 10, 15, or 20 min post-coagulation followed by heating and stretching. MF Mozzarella was also made in triplicate at treatment midpoints using 2%
starter culture. Cheeses were not compositionally different and met legal standards for LMPS Mozzarella. A yield increase of 14.9 percent was realized due to incorporation of 31.1 percent feed whey protein and 98.2 percent fat retention. Loss of total solids and protein to whey was minimized at lowest Conc and Time, with decreasing Conc increasing loss of ash and Ca to whey. Increased Conc significantly increased pH 4.6 soluble N in cheese. Using GDL, 12 percent TCA soluble N changed little through 60 days of age, but when starter culture was used both measures of soluble N increased significantly. Rheological differences were quantified by stress relaxation and squeezing flow tests. Conc was the only significant factor in lessening cheese rigidity and increasing flowability. Rheological change in MF Mozzarella (using GDL) occurred primarily between 30 and 60 days of age, but with more rapid change in structure occurring with use of starter culture. Optimal MF cheesemaking conditions
were 80 ml rennet/kg cheesemilk, 36C Temp, and 15 min Time. Use of starter culture or other adjunct proteases is essential to promote typical rheological development of MF Mozzarella.
Impacts
(N/A)
Publications
- No publications reported this period
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