Standardization of milk using cold ultrafiltration retentates for the manufacture of Swiss cheese: effect of altering coagulation conditions on yield and cheese quality

Fortification of cheesemilk with membrane retentates is often practiced by cheesemakers to increase yield. However, the higher casein (CN) content can alter coagulation characteristics, which may affect cheese yield and quality. The objective of this study was to evaluate the effect of using ultrafiltration (UF) retentates that were processed at low temperatures on the properties of Swiss cheese. Because of the faster clotting observed with fortified milks, we also investigated the effects of altering the coagulation conditions by reducing the renneting temperature (from 32.2 to 28.3°C) and allowing a longer renneting time before cutting (i.e., giving an extra 5 min). Milks with elevated total solids (TS; ∼13.4%) were made by blending whole milk retentates (26.5% TS, 7.7% CN, 11.5% fat) obtained by cold (<7°C) UF with part skim milk (11.4% TS, 2.5% CN, 2.6% fat) to obtain milk with CN:fat ratio of approximately 0.87. Control cheeses were made from part-skim milk (11.5% TS, 2.5% CN, 2.8% fat). Three types of UF fortified cheeses were manufactured by altering the renneting temperature and renneting time: high renneting temperature = 32.2°C (UFHT), low renneting temperature = 28.3°C (UFLT), and a low renneting temperature (28.3°C) plus longer cutting time (+5 min compared to UFLT; UFLTL). Cutting times, as selected by a Wisconsin licensed cheesemaker, were approximately 21, 31, 35, and 32 min for UFHT, UFLT, UFLTL, and control milks, respectively. Storage moduli of gels at cutting were lower for the UFHT and UFLT samples compared with UFLTL or control. Yield stress values of gels from the UF-fortified milks were higher than those of control milks, and decreasing the renneting temperature reduced the yield stress values. Increasing the cutting time for the gels made from the UF-fortified milks resulted in an increase in yield stress values. Yield strain values were significantly lower in gels made from control or UFLTL milks compared with gels made from UFHT or UFLT milks. Cheese composition did not differ except for fat content, which was lower in the control compared with the UF-fortified cheeses. No residual lactose or galactose remained in the cheeses after 2 mo of ripening. Fat recoveries were similar in control, UFHT, and UFLTL but lower in UFLT cheeses. Significantly higher N recoveries were obtained in the UF-fortified cheeses compared with control cheese. Because of higher fat and CN contents, cheese yield was significantly higher in UF-fortified cheeses (∼11.0 to 11.2%) compared with control cheese (∼8.5%). A significant reduction was observed in volume of whey produced from cheese made from UF-fortified milk and in these wheys, the protein was a higher proportion of the solids. During ripening, the pH values and 12% trichloroacetic acid-soluble N levels were similar for all cheeses. No differences were observed in the sensory properties of the cheeses. The use of UF retentates improved cheese yield with no significant effect on ripening or sensory quality. The faster coagulation and gel firming can be decreased by altering the renneting conditions.     

Standardization of milk using cold ultrafiltration retentates for the manufacture of parmesan cheese

The effects of using cold ultrafiltered (UF) retentates (both whole and skim milk) on the coagulation, yield, composition, and ripening of Parmesan cheese were investigated. Milks for cheese making were made by blending cold UF retentates with partially skimmed milk to obtain blends with 14.2% solids and a casein:fat ratio of 1.1. Cutting times, as selected by the cheese-maker, were approximately 15 and approximately 20 min for experimental and control milks, respectively. Storage modulus values at cutting were similar, but yield stress values were significantly higher in UF retentate standardized milks. Cheese yields were significantly higher in UF retentate standardized milks (approximately 12%) compared with control milk (cream removed) (approximately 7 to 8%). Significantly higher protein recoveries were obtained in cheeses manufactured using cold UF retentates. There were no differences in the pH and moisture contents of the cheeses prior to brining, and there was no residual lactose or galactose left in the cheeses. Using UF retentates resulted in a significant reduction in whey volume as well as a higher proportion of protein in the solids of the whey. Proteolysis, free fatty acids, and sensory properties of the cheeses were similar. The use of milk concentrated by cold UF is a promising way of improving the yield of Parmesan cheese without compromising cheese quality. The question remaining to be answered by the cheesemaker is whether it is economical to do so.     

Use of cold microfiltration retentates produced with polymeric membranes for standardization of milks for manufacture of pizza cheese

Pizza cheese was manufactured with milk (12.1% total solids, 3.1% casein, 3.1% fat) standardized with microfiltered (MF) and diafiltered retentates. Polymeric, spiral-wound MF membranes were used to process cold (<7°C) skim milk, and diafiltration of MF retentates resulted in at least 36% removal of serum protein on a true protein basis. Cheese milks were obtained by blending the MF retentate (16.4% total solids, 11.0% casein, 0.4% fat) with whole milk (12.1% total solids, 2.4% casein, 3.4% fat). Control cheese was made with part-skim milk (10.9% total solids, 2.4% casein, 2.4% fat). Initial trials with MF standardized milk resulted in cheese with approximately 2 to 3% lower moisture (45%) than control cheese (∼47 to 48%). Cheese-making procedures (cutting conditions) were then altered to obtain a similar moisture content in all cheeses by using a lower setting temperature, increasing the curd size, and lowering the wash water temperature during manufacture of the MF cheeses. Two types of MF standardized cheeses were produced, one with preacidification of milk to pH 6.4 (pH6.4MF) and another made from milk preacidified to pH 6.3 (pH6.3MF). Cheese functionality was assessed by dynamic low-amplitude oscillatory rheology, University of Wisconsin MeltProfiler, and performance on pizza. Nitrogen recoveries were significantly higher in MF standardized cheeses. Fat recoveries were higher in the pH6.3MF cheese than the control or pH6.4MF cheese. Moisture-adjusted cheese yield was significantly higher in the 2 MF-fortified cheeses compared with the control cheese. Maximum loss tangent (LT_max) values were not significantly different among the 3 cheeses, suggesting that these cheeses had similar meltability. The LT_max values increased during ripening. The temperature at which the LT_max was observed was highest in control cheese and was lower in the pH6.3MF cheese than in the pH6.4MF cheese. The temperature of the LT_max decreased with age for all 3 cheeses. Values of 12% trichloroacetic acid soluble nitrogen levels were similar in all cheeses. Performance on pizza was similar for all cheeses. The use of MF retentates derived with polymeric membranes was successful in increasing cheese yield, and cheese quality was similar in the control and MF standardized cheeses.     

Effect of type of concentrated sweet cream buttermilk on the manufacture, yield, and functionality of pizza cheese

Sweet cream buttermilk (SCB) is a rich source of phospholipids (PL). Most SCB is sold in a concentrated form. This study was conducted to determine if different concentration processes could affect the behavior of SCB as an ingredient in cheese. Sweet cream buttermilk was concentrated by 3 methods: cold ( < 7°C) UF, cold reverse osmosis (RO), and evaporation (EVAP). A washed, stirred-curd pizza cheese was manufactured using the 3 different types of concentrated SCB as an ingredient in standardized milk. Cheesemilks of casein:fat ratio of 1.0 and final casein content ∼2.7% were obtained by blending ultrafiltered (UF)-SCB retentate (19.9% solids), RO-SCB retentate (21.9% solids), or EVAP-SCB retentate (36.6% solids) with partially skimmed milk (11.2% solids) and cream (34.6% fat). Control milk (11.0% solids) was standardized by blending partially skimmed milk with cream. Cheese functionality was assessed using dynamic low-amplitude oscillatory rheology, UW Meltprofiler (degree of flow after heating to 60°C), and performance of cheese on pizza. Initial trials with SCB-fortified cheeses resulted in ∼4 to 5% higher moisture (51 to 52%) than control cheese (∼47%). In subsequent trials, procedures were altered to obtain similar moisture content in all cheeses. Fat recoveries were significantly lower in RO- and EVAP-SCB cheeses than in control or UF-SCB cheeses. Nitrogen recoveries were not significantly different but tended to be slightly lower in control cheeses than the various SCB cheeses. Total PL recovered in SCB cheeses (∼32 to 36%) were lower than control (∼41%), even though SCB is high in PL. From the rheology test, the loss tangent curves at temperatures > 40°C increased as cheese aged up to a month and were significantly lower in SCB cheeses than the control, indicating lower meltability. Degree of flow in all the cheeses was similar regardless of the treatment used, and as cheese ripened, it increased for all cheeses. Trichloroacetic acid-soluble N levels were similar in the control and SCB-fortified cheese. On baked pizza, cheese made from milk fortified with UF-SCB tended to have the lowest amount of free oil, but flavor attributes of all cheeses were similar. Addition of concentrated SCB to standardize cheesemilk for pizza cheese did not adversely affect functional properties of cheese but increased cheese moisture without changes in manufacturing procedure.     

Cheddar Cheese from Water Reconstituted Retentates

Reconstituted creamed retentates of ultrafiltration were converted to ripened cheese by Cheddar manufacturing principles. Initially, the fresh cheeses resembled normal Cheddar but during ripening were transformed into Gouda-Swiss types with pH rising rapidly from 5.2 to approximately 6.0.Cheese composition was affected by amount of full fat retentate in reconstituted mixtures. As total milk solids increased in reconstituted retentates, cheese moisture decreased and cheese volume rose to high yields. Cheese yield efficiency showed 1.21 to 1.32 kg cheese per kg total solids. Rennet curd of higher total solids retentates formed more rapidly than normal, and curds were harder. Whey from retentate reconstituted cheeses showed relatively low ash and fat even from cheeses made with high retentate. Soluble protein in 2-mo-old cheeses held at 10° C was lower in cheese from retentates of high solids.     

Slower proteolysis in Cheddar cheese made from high-protein cheese milk is due to an elevated whey protein content

A growing number of companies within the cheese-making industry are now using high-protein (e.g., 4–5%) milks to increase cheese yield. Previous studies have suggested that cheeses made from high-protein (both casein and whey protein; WP) milks may ripen more slowly; one suggested explanation is inhibition of residual rennet activity due to elevated WP levels. We explored the use of microfiltration (MF) to concentrate milk for cheese-making, as that would allow us to concentrate the casein while varying the WP content. Our objective was to determine if reducing the level of WP in concentrated cheese milk had any impact on cheese characteristics, including ripening, texture, and nutritional profile. Three types of 5% casein standardized and pasteurized cheese milks were prepared that had various casein:true protein (CN:TP) ratios: (a) control with CN:TP 83:100, (b) 35% WP reduced, 89:100 CN:TP, and (c) 70% WP reduced, 95:100 CN:TP. Standardized milks were preacidified to pH 6.2 with dilute lactic acid during cheese-making. Composition, proteolysis, textural, rheological, and sensory properties of cheeses were monitored over a 9-mo ripening period. The lactose, total solids, total protein, and WP contents in the 5% casein concentrated milks were reduced with increasing levels of WP removal. All milks had similar casein and total calcium levels. Cheeses had similar compositions, but, as expected, lower WP levels were observed in the cheeses where WP depletion by MF was performed on the cheese milks. Cheese yield and nitrogen recoveries were highest in cheese made with the 95:100 CN:TP milk. These enhanced recoveries were due to the higher fraction of nitrogen being casein-based solids. Microfiltration depletion of WP did not affect pH, sensory attributes, or insoluble calcium content of cheese. Proteolysis (the amount of pH 4.6 soluble nitrogen) was lower in control cheeses compared with WP-reduced cheeses. During ripening, the hardness values and the temperature of the crossover point, an indicator of the melting point of the cheese, were higher in the control cheese. It was thus likely that the higher residual WP content in the control cheese inhibited proteolysis during ripening, and the lower breakdown rate resulted in its higher hardness and melting point. There were no major differences in the concentrations of key nutrients with this WP depletion method. Cheese milk concentration by MF provides the benefit of more typical ripening rates.     

Cottage Cheese from Ultrafiltered Skim Milk Retentates in Industrial Cheese Making

Ultrafiltered skim milk retentates were transported to a large industrial cottage cheese plant for milk supplementation leading to cottage cheese. The resulting industrial products were observed for composition, yields, whey component losses, and quality.Ten lots of small curd cottage cheese were made in vats containing up to 6593 kg skim milk. Retentate supplemented skim milks, concentrated approximately 10% (1.1:1) and 20% (1.2:1) in total protein, were very similar in initial composition to the controls. Mean cheese yield values from milks supplemented to 1.2:1 total protein were significantly higher than mean unsupplemented control milk values. Cheese yield efficiencies, per kilogram total solids, were also significantly higher in the retentate cheese but not when calculated per kilogram total protein.Total solids, total protein, and ash were higher in cottage cheese wheys from retentate supplemented cheese and were directly related to retentate supplementation concentration. Mean whey component loss per kilogram cheese exhibited significant decreases from milks of higher retentate supplementation. Retentate supplemented skim milk produced industrial cottage cheese of comparable quality to cheese made from unsupplemented control skim milks.     

Cheddar Cheese from Ultrafiltered Whole Milk Retentates in Industrial Cheese Making

Transporting whole milk retentates of ultrafiltration to a distant large industrial Cheddar cheese making site resulted in 16 lots of Cheddar cheese from vats containing 2,546 to 16,360 kg of cheese milk. Whole milk retentates concentrated by ultrafiltration to 4.5:1 were added to cheese milks to give mixtures concentrated 1.2:1 and 1.3:1 with approximately 20 and 30% more protein and fat, respectively, than in unsupplemented control whole milks or unsupplemented commercial reference milks.Gross composition of Cheddar cheese made from commercial reference, control, and retentate-supplemented milk generally showed no major differences. Yield increased in cheese made from retentate-supplemented milk. Yield efficiency per kilogram total solids rose in retentate cheese over controls but not among commercial reference, control, and retentate lots based on per kilogram fat or total protein. Milk components were higher in wheys from retentate cheeses, but loss of components per kilogram cheese obtained generally showed lower values in whey from retentate cheese.General quality of retentate Cheddar cheese was equal to that of reference unsupplemented commercial cheese and higher than unsupplemented control Cheddar cheeses. It appears technically feasible to ultrafilter milk at one site, such as the farm, collecting station, or specialized center, and transport it to an industrial site for Cheddar cheese making.     

Effect of lactose standardization of milk using low-concentration factor ultrafiltration: Effect of reducing the lactose-to-casein ratio on the properties of milled-curd Cheddar cheese

The pH of cheese is determined by the amount of lactose fermented and the buffering capacity of the cheese. The buffering capacity of cheese is largely determined by the protein contents of milk and cheese and the amount of insoluble calcium phosphate in the curd, which is related to the rate of acidification. The objective of this study was to standardize both the lactose and casein contents of milk to better control final pH and prevent the development of excessive acidity in Cheddar cheese. This approach involved the use of low-concentration factor ultrafiltration of milk to increase the casein content (～5%), followed by the addition of water, ultrafiltration permeate, or both to the retentate to adjust the lactose content. We evaluated milks with 4 different lactose-to-casein ratios (L:CN): 1.8 (control milk), 1.4, 1.1, and 0.9. All cheesemilks had similar total casein (2.3%) and fat (3.4%) contents. These milks were used to make milled-curd Cheddar cheese, and we evaluated cheese composition, texture, functionality, and sensory properties over 9 mo of ripening. Cheeses made from milks with varying levels of L:CN had similar moisture, protein, fat, and salt contents, due to slight modifications during manufacture (i.e., cutting the gel at a smaller size than control) as well as control of acid development at critical steps (i.e., cutting the gel, whey drainage, salting). As expected, decreasing the L:CN led to cheeses with lower lactic acid, residual lactose, and insoluble Ca contents, as well as a substantial pH increase during cheese ripening in cheeses. The L:CN ratio had no significant effect on the levels of primary and secondary proteolysis. Texture profile analysis showed no significant differences in hardness values during ripening. Maximum loss tangent, an index of cheese meltability, was lower until 45 d for the L:CN 1.4 and 0.9 treatments, but after 45 d, all reduced L:CN cheeses had higher maximum loss tangent values than the control cheese (L:CN 1.8). Sensory analyses showed that cheeses made from milks with reduced L:CN contents had lower acidity, sourness, sulfury notes, and chewdown cohesiveness. Standardization of milk to a specific L:CN ratio, while maintaining a constant casein level in the milk, would allow Cheddar cheese manufacturers to have tighter control of pH and acidity.     

Characterization of Nitrogen Fractions During Ripening of a Soft Cheese Made from Ultrafiltration Retentates

Nitrogen fractions of a soft cheese made from UF retentates were used to characterize the ripening of the cheese. Whole milk was fractionated, using UF and diafiltration to a retentate concentration factor of five times. Control and experimental soft, white cheeses were made from whole milk and UF retentate, respectively. Both cheeses were ripened at 8°C for 21 d and analyzed at 7-d intervals. Nitrogen fractions were separated and discontinuous PAGE was used to characterize total protein and whey protein. A ripening extension index related to rennet activity was determined based on the ratio of soluble N to total N. A ripening depth index related to starter peptidase activity was determined by the ratio nonprotein N/total N. Increases in ripening extension index and ripening depth were higher (48.45 and 18.56%, respectively) in UF cheese than in regular cheese (41.06 and 17.11%, respectively). The N fractions soluble in 20% sodium sulfate were composed mainly of bovine serum albumin, β-lactoglobulin A and B, and α-lactalbumin in fresh and ripened UF cheese. Whey protein N represented about 17 and .5% of total N in UF and regular cheese, respectively. No significant breakdown was detected in the whey protein N fraction in the UF cheese.     

The behavior of selected microorganisms during the manufacture of high moisture Jack cheeses from ultrafiltered milk.

Whole milk was pasteurized and concentrated two times by ultrafiltration. Starter cultures, Lactococcus lactis ssp. cremoris and Lactococcus lactis ssp. lactis, were propagated in either reconstituted skim milk, two times UF retentate, or UF permeate, or a direct vat system was used for the starter culture. The cheese milk was simultaneously inoculated with starter culture and Pseudomonas fragi 4973, Staphylococcus aureus 196E, and Salmonella typhimurium var. Hillfarm. Control whole milk, UF control milk, inoculated whole milk, and inoculated UF milk were made into Monterey Jack cheese using traditional procedures. The process of cheese manufacture was followed by determination of pH, titratable acidity, and microbial population levels. The cheeses were stored for 6 mo and analyzed every month for percentage solids and microbial population levels. Generally, numbers of contaminant microbes increased at a similar rate during manufacture in all cheeses. During the 6-mo ripening period, bacterial starter culture population levels remained high, psychrotrophs declined slowly, Staphylococcus levels remained stable, and Salmonella populations decreased. No Staphylococcus enterotoxin was detected by reverse passive latex agglutination assay.     

Blue like cheese from dried milk

A trial was made to produce Blue like cheese from both whole dry milk and non fat one. The resultant cheese was kept for ripening at 5°C for two months. Cheese made from reconstituted whole dried milks were characterized with higher moisture, salt, and protein contents and acidity than the control. Protein degradation and fat hydrolysis were found to be lower in these cheeses than the control. Organoleptically, cheese made from cow's milk was found to be superior to cheeses produced from reconstituted either non fat or whole dried milk, as regards flavour, body and texture and the distribution of P. requeforti.     

Evaluation of biogenic amines and microbial counts throughout the ripening of goat cheeses from pasteurized and raw milk

The effect of the hygienic quality of milk on changes in microbial counts and biogenic amine content was evaluated during ripening of goat cheeses manufactured from pasteurized and raw milks at 1, 14, 30, 60 and 90 d. The original milk, rennet, curd and whey were also included in the study. The pH, salt content and extent of proteolysis in the cheese were also evaluated. Spermidine and spermine were the main amines in raw milk, while they were minor amines in cheeses. Other amines increased markedly during ripening, tyramine being the main amine in cheese made from raw milk and cadaverine and putrescine in those produced from pasteurized milk. Enterobacteriaceae counts decreased during ripening whereas those of lactic acid bacteria increased, especially lactobacilli and enterococci. Cheese made from raw milk showed higher microbial counts during ripening than those made from pasteurized milk, especially for Enterobacteriaceae and enterococci, counts being 2 or 3 log units higher. Raw milk cheese showed remarkably higher biogenic amines compared with pasteurized milk cheeses. Therefore, pasteurization of milk causes a decrease in final biogenic amine content of cheese as a result of the reduction of its microbial counts.     

Effect of camel chymosin on the texture,functionality, and sensory properties of low-moisture,part-skim Mozzarella cheese

The objective of this study was to compare the effect of coagulant (bovine calf chymosin, BCC, or camel chymosin, CC), on the functional and sensory properties and performance shelf-life of low-moisture, part-skim (LMPS) Mozzarella. Both chymosins were used at 2 levels [0.05 and 0.037 international milk clotting units (IMCU)/mL], and clotting temperature was varied to achieve similar gelation times for each treatment (as this also affects cheese properties). Functionality was assessed at various cheese ages using dynamic low-amplitude oscillatory rheology and performance of baked cheese on pizza. Cheese composition was not significantly different between treatments. The level of total calcium or insoluble (INSOL) calcium did not differ significantly among the cheeses initially or during ripening. Proteolysis in cheese made with BCC was higher than in cheeses made with CC. At 84 d of ripening, maximum loss tangent values were not significantly different in the cheeses, suggesting that these cheeses had similar melt characteristics. After 14 d of cheese ripening, the crossover temperature (loss tangent = 1 or melting temperature) was higher when CC was used as coagulant. This was due to lower proteolysis in the CC cheeses compared with those made with BCC because the pH and INSOL calcium levels were similar in all cheeses. Cheeses made with CC maintained higher hardness values over 84 d of ripening compared with BCC and maintained higher sensory firmness values and adhesiveness of mass scores during ripening. When melted on pizzas, cheese made with CC had lower blister quantity and the cheeses were firmer and chewier. Because the 2 types of cheeses had similar moisture contents, pH values, and INSOL Ca levels, differences in proteolysis were responsible for the firmer and chewier texture of CC cheeses. When cheese performance on baked pizza was analyzed, properties such as blister quantity, strand thickness, hardness, and chewiness were maintained for a longer ripening time than cheeses made with BCC, indicating that use of CC could help to extend the performance shelf-life of LMPS Mozzarella.     

Manufacture and quality of UF Ras cheese

Ras cheese was made by means of the traditional method from cow's milk and milk concentrated by ultrafiltration to concentration factors 2 and 5, and from diafiltered x5 retentate. The fresh cheese yield was determined and cheese was ripened for 3 months, changes in moisture, fat, nitrogen fractions, pH, acidity and ripening indices were followed periodically during the ripening period. The organoleptic properties of the cheese were also assessed. UF Milk retentate gave higher cheese yield depending on concentration factor. UF Ras cheese from high concentrated retentate was characterized by slow protein degradation, flavour development and hard texture. The composition and properties of UF Ras cheese from x2 retentate were close to that of traditional Ras cheese.     

The manufacture of miniature Cheddar-type cheeses from milks with different fat globule size distributions

A novel 2-stage gravity separation scheme was developed for fractionation of raw, whole bovine milk into fractions enriched in small (SFG) or large (LFG) fat globules. The volume mean diameter of fat globules in SFG, LFG or control (CTRL) milk was 3.45, 4.68 and 3.58 microm, respectively. The maximum in storage modulus (index of firmness) decreased with increasing fat globule size for rennet-induced gels formed from SFG, LFG or CTRL milks. Miniature (20 g) Cheddar cheeses were manufactured using each of the 3 milks. There were no significant (P > 0.05) differences in the pH, moisture and fat in dry matter levels between cheeses made using any of the 3 milks, however, the fat content of the cheese made using SFG milk was approximately 1% lower than that of cheese made using LFG or CTRL milk in each of the 2 trials. Image analysis of confocal scanning laser micrographs of the cheeses illustrated that the star volume of fat globules in the cheeses decreased significantly (P < or = 0.05) as the size of fat globules in the milks used for cheesemaking was reduced. This indicates that it is possible to manipulate the size distribution of fat globules in Cheddar cheese by adjusting the fat globule size distribution of the milk used for cheese-making. The concentration of free fatty acids (FFA) increased in all cheeses during ripening. At 120 d of ripening, the concentration of FFA varied significantly (P < or = 0.05 and P < or = 0.001 for trials 1 and 2, respectively) with fat globule size, with cheeses made in trial 2 from LFG, SFG or CTRL milks having total FFA levels of 3391, 2820 and 2612 mg/kg cheese, respectively.     

Effect of β-casein concentration in cheese milk on rennet coagulation properties,cheese composition and cheese ripening

Effects of the use of a β-casein powder to enrich cheese milk on rennet coagulation properties of milk, cheese composition and cheese ripening were investigated. Casein content of control milk was 2.5%, whereas that for the three enriched milks was adjusted with β-casein powder at 2.7%, 2.9% and 3.1%. The β-casein to α-casein ratio of these cheese milks was, respectively, 0.70, 0.79, 0.89 and 0.99. Rennet coagulation properties were related not only to casein concentration but also to the proportion of β-casein and α_s-casein presents in milks. Milk with higher concentration of β-casein had poorer coagulation properties. Cheeses could be produced by using a miniature cheese making process. Moisture, ash and calcium contents decreased, while protein content and β-casein increased in cheese as casein and β-casein concentration increased in milk. As a result, hardness was higher in enriched cheeses than in control cheese. During cheese ripening, α-casein was hydrolyzed, but the rate of degradation of α-casein decreased as protein and β-casein concentration increased in cheese. β-Casein seemed to be not hydrolyzed. The rate of decrease of hardness was also slower for enriched cheeses.     

Microbiological changes throughout ripening of goat cheese made from raw,pasteurized and high-pressure-treated milk

The bacteriological quality during ripening of raw (RA), pasteurized (PA; 72°C, 15 s) and pressure-treated (PR; 500 MPa, 20°C, 15 min) goat milk assessed by enumeration of total bacteria, psychrotrophic bacteria, Enterobacteriaceae, lactobacilli, enterococci, Micrococcaceae and lactococci was evaluated. The high pressure treatment applied was as efficient as pasteurization in reducing the bacterial population of milk. Experimental cheeses were made from RA, PA and PR milks to study the microbial population during ripening. Lactobacilli and lactococci were the predominant microbiota present during ripening in all the cheeses. There were no differences in numbers of starter bacteria during ripening. However, lactobacilli counts for RA milk cheese were significantly higher than for PA and PR cheeses in all the ripening stages studied. Micrococcaceae and enterococci remained at a secondary level, and no differences were observed between cheeses at the end of ripening. On the other hand, the number of Enterobacteriaceae decreased during ripening, but faster in PR milk cheese than in PA and RA milk cheeses. The results of this study suggest that goat cheese made from PR milk had similar microbiological characteristics to PA milk cheeses.     

Physical Properties of Direct Acidified Mozzarella Cheese from Ultrafiltered Whole Milk Retentates

Retentates from ultrafiltration of pasteurized whole milk at three volume concentration ratios, 1.4:1, 1.7:1 and 2:1. were made into Mozzarella cheese by direct acidification with 10% glacial acetic acid.Excellent melting Mozzarella cheese was attained and increases in cheese yield were related directly to retentate concentration. Yield efficiency, based on casein recovery, was higher in retentate cheese than in controls. Cheese from ultrafiltered whole milk using low concentrated retentates generally showed improved physical properties over that of nonretentate control whole milks. Composition of direct acidified cheese from whole milk retentates when compared with federal standards of identity fitted those of low moisture Mozzarella rather than Mozzarella.     

Effect of somatic cell count in goat milk on yield, sensory quality, and fatty acid profile of semisoft cheese

This study investigated the effect of somatic cell count (SCC) in goat milk on yield, free fatty acid (FFA) profile, and sensory quality of semisoft cheese. Sixty Alpine goats without evidence of clinical mastitis were assigned to 3 groups with milk SCC level of <500,000 (low), 500,000 to 1,000,000 (medium), and 1,000,000 to 1,500,000 (high) cells/mL. Thirty kilograms of goat milk with mean SCC levels of 410,000 (low), 770,000 (medium), and 1,250,000 (high) cells/mL was obtained for the manufacture of semisoft cheese for 2 consecutive weeks in 3 lactation stages. The composition of milk was analyzed and cheese yield was recorded on d 1. Cheese samples on d 1, 60, and 120 were analyzed for total sensory scores, flavor, and body and texture by a panel of 3 expert judges and were also analyzed for FFA. Results indicated that milk composition did not change when milk SCC varied from 214,000 to 1,450,000 cells/mL. Milk with higher SCC had a lower standard plate count, whereas coliform count and psychrotrophic bacteria count were not affected. However, milk components (fat, protein, lactose, casein, and total solids) among the 3 groups were similar. As a result, no significant differences in the yield of semisoft goat cheeses were detected. However, total sensory scores and body and texture scores for cheeses made from the high SCC milk were lower than those for cheeses made from the low and medium SCC milks. The difference in milk SCC levels also resulted in diverse changes in cheese texture (hardness, springiness, and so on) and FFA profiles. Individual and total FFA increased significantly during ripening, regardless the SCC levels. It is concluded that SCC in goat milk did not affect the yield of semisoft cheese but did result in inferior sensory quality of aged cheeses.