Application of Retentate Starter Produced from Ultrafiltered Milk to the Manufacture of Cheddar Cheese

Cheddar cheese was manufactured from whole milk and whole milk retentate using retentate starter made from milk ultrafiltered to 4:1 (vol/vol). One percent retentate starter added to whole milk and 2% starter to 1.7:1 whole milk retentate gave excellent quality cheese. Additionally, a 1% retentate starter added to whole milk gave approximately 3% more cheese. A 2% retentate starter added to 1.7:1 whole milk retentate gave 4% more cheese, reduced cheese making time over that required for control whole milk cheese, and made acid ripening of milk before renneting unnecessary. Starter concentrations above 1% in whole milk and above 2% in whole milk retentates produced some bitterness in the cheese.     

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.     

Low Moisture Mozzarella Cheese from Whole Milk Retentates of Ultrafiltration

Whole milk retentates, prepared by ultrafiltration of pasteurized milk to volume concentration ratios of 1.5:1, 1.75:1, and 2:1, were made into low moisture Mozzarella cheese using thermophilic bacterial cultures.Good melting properties, increased output per vat, and higher yield efficiency based on total solids were observed in retentate over control cheese. Optimum retentate volume concentration ratio was 1.75:1. Cheese from 2:1 volume concentration ratio retentates had desirable qualities but were firmer with greater whey fat losses than cheese from non-retentate controls or 1.5:1, and 1.75:1 volume concentration ratio retentates. Composition of cheese made from whole milk retentates using thermophilic starters complied with US federal standards of identity for low moisture Mozzarella cheese.     

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.     

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.     

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.     

Rheological properties and microstructure during rennet induced coagulation of UF concentrated skim milk

Rennet induced coagulation of ultrafiltrated (UF) skim milk (19.8%, w/w casein) at pH 5.8 was studied and compared with coagulation of unconcentrated skim milk of the same pH. At the same rennet concentration (0.010 International Milk Clotting Units g⁻¹), coagulation occurred at a slower rate in UF skim milk but started at a lower degree of κ-casein hydrolysis compared with the unconcentrated skim milk. Confocal laser scanning micrographs revealed that large aggregates developed in the unconcentrated skim milk during renneting. Following extensive microsyneresis the protein strands were shorter and thinner in gels from UF skim milk. Moreover, during storage up to 60 days (13 °C), the microstructure and the size of the protein strands of the UF gel changed only slightly. Hoelter–Foltmann plots suggested that the coagulation rate was reduced in the UF skim milk due to a high zero shear viscosity of the concentrate compared with the unconcentrated skim milk.     

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.     

Manufacture of heat and acid coagulated cheese from ultrafiltered milk retentates

Ultrafiltration technology was used for the production of direct acidified cheese. Process parameters were optimized for cheese manufacture from whole milk retentates at 4:1 volume concentration ratio. Sensory evaluation indicated that cheese from ultrafiltration was preferred equally to traditional manufacture when the cheese was of similar composition, while citric acid was the preferred acidulent. An increase in cheese yield of 3.3% and an increase in yield on dry matter mass basis of 14.7% was achieved by use of ultrafiltration. Yield efficiencies based on protein, fat or total solids increased with retentate concentration.     

Ultrafiltration of Milk on French Farms and in the Making of a New Specialty Cheese Industry

Ultrafiltration and thermization of milk on dairy farms in France have been under study since 1979. More recently five dairy farms in Brittany have been routinely producing 2:1 whole milk retentate for Emmental and St. Paulin cheese making. The milk processed is ultrafiltered at 35°C and thermized at 72°C for 15 s in an Ultratherm unit. Cheese quality generally appears satisfactory.In Eastern France a new specialty cheese industry has been started utilizing 4.5:1 whole milk retentate produced by ultrafiltration conducted at 40°C. The specialty cheese attains its characteristic white surface from Penicillium album mold. It has a bland, nutty flavor and very soft, smooth texture. A surface bluing phenomenon occurs after 14 d.     

Vatless manufacturing of low-moisture part-skim mozzarella cheese from highly concentrated skim milk microfiltration retentates

Low-moisture, part-skim (LMPS) Mozzarella cheeses were made from concentration factor (CF) 6, 7, 8, and 9, pH 6.0 skim milk microfiltration (MF) retentates using a vatless cheese-making process. The compositional and proteolytic effects of cheese made from 4 CF retentates were evaluated as well as their functional properties (meltability and stretchability). Pasteurized skim milk was microfiltered using a 0.1-microm ceramic membrane at 50 degrees C to a retentate CF of 6, 7, 8, and 9. An appropriate amount of cream was added to achieve a constant casein:fat ratio in the 4 cheesemilks. The ratio of rennet to casein was also kept constant in the 4 cheesemilks. The compositional characteristics of the cheeses made from MF retentates did not vary with retentate CF and were within the legal range for LMPS Mozzarella cheese. The observed reduction in whey drained was greater than 90% in the cheese making from the 4 CF retentates studied. The development of proteolytic and functional characteristics was slower in the MF cheeses than in the commercial samples that were used for comparison due to the absence of starter culture, the lower level of rennet used, and the inhibition of cheese proteolysis due to the inhibitory effect of residual whey proteins retained in the MF retentates, particularly high molecular weight fractions.     

Short communication: Calcium partitioning during microfiltration of milk and its influence on rennet coagulation time

Pasteurized skim milk was subjected to (1) microfiltration (MF) at 50°C and (2) MF at 6°C after storage at 2°C. The products of these treatments were retentate (RMF50) and permeate (PMF50), and retentate (RMF6) and permeate (PMF6), respectively. Additionally, RMF50 was subjected to (3) cold MF after water dilution to produce retentate (RMF6R) and permeate (PMF6R). Calcium migration was monitored by analyzing ionic, soluble, and total calcium content in feed, retentates, and permeates. The influence of calcium partitioning and calcium addition to feed, retentates, and retentates diluted with water was determined. Without CaCl₂ addition, only skim milk, RMF50, and RMF6 coagulated after rennet addition. Higher true protein and casein content of RMF50 and RMF6 resulted in shorter time of renneting. The retentates diluted with water showed no signs of coagulation within 40 min. The addition of PMF6R to RMF50 did not affect rennet coagulation time within the observed 40 min in comparison to RMF50 + water. In general, higher CaCl₂ addition resulted in shorter rennet coagulation time. Special attention should be paid to calcium partitioning during membrane processing of cheesemilk. The level of calcium addition should be adopted to calcium content in such cheesemilk, which is affected by conditions of the filtration process (i.e., concentration factor and temperature).     

Cathepsin D activity in quarg

Quarg cheese was produced from raw skim milk, pasteurised skim milk, raw skim milk with rennet added and ultrafiltrated raw skim milk. Quarg was also produced from raw skim milk with pepstatin added at curd cutting and from ultrafiltration retentate of raw milk with added pepstatin. No starter bacteria were used in this model system, with the reduction of pH being achieved by addition of glucono- δ-lactone. Yields ranged between 20.25 and 23.5%, with protein levels of 13.6–15.7%. Proteolysis occurred during storage of all experimental cheese samples for 3 m at 8°C. By immunoblotting using antibodies against bovine cathepsin D, immunoreactive procathepsin D was identified in all cheese samples. Presence of cathepsin D or procathepsin D-derived activity was confirmed by a specific enzyme assay in all samples, except those which contained pepstatin. Inhibition of cathepsin D-catalysed proteolysis by pepstatin was observed in chromatograms of water-soluble extracts analysed by reverse-phase HPLC. Peptides thought to be produced as a result of cathepsin D activity were observed in cheese made from both raw and pasteurised milk, suggesting that the activity at least partially survived pasteurisation.     

Manufacture of direct acidified cheese from ultrafiltration and reverse osmosis retentates

Whole milk and retentates from ultrafiltration at 4:1 volume concentration ratio and reverse osmosis at 2.5:1 were used in the manufacture of direct acidified cheese. Yield based on component recovery was higher in cheese from milk retentates than whole milk. On a dry mass basis, an increase in cheese yield of 37.9% for reverse osmosis, and 14.7% for ultrafiltration was achieved compared with cheese from whole milk. Compositional variation in the resulting cheese affected both textural and sensory parameters. Cheese from ultrafiltration scored highest in sensory evaluation, although all cheeses were graded fair to good.     

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.     

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.     

Fermentation of Ultrafiltered Skim Milk Retentates with Mesophilic Lactic Cheese Starters

Acid production and its relation to pH changes by commercial, direct-set frozen concentrated lactic starters in skim milk and 2:1 skim milk retentates were studied. Retentates resisted pH change below pH 5.2 despite the production of large amounts of lactic acid by starter bacteria. Control skim milk required 6 h at 32°C to attain pH 4.6, but skim milk retentates incubated similarly could not be fermented to this pH even after 8.5 h. Doubling the starter inoculum in the retentate led to pH 4.6 in 7.5 h. Direct-set starter DS1, with more bacteria numbers than direct-set starter DS2, fermented skim milk and 2:1 skim milk retentate more rapidly.     

A microfiltration process to maximize removal of serum proteins from skim milk before cheese making

Microfiltration (MF) is a membrane process that can separate casein micelles from milk serum proteins (SP), mainly beta-lactoglobulin and alpha-lactalbumin. Our objective was to develop a multistage MF process to remove a high percentage of SP from skim milk while producing a low concentration factor retentate from microfiltration (RMF) with concentrations of soluble minerals, nonprotein nitrogen (NPN), and lactose similar to the original skim milk. The RMF could be blended with cream to standardize milk for traditional Cheddar cheese making. Permeate from ultrafiltration (PUF) obtained from the ultrafiltration (UF) of permeate from MF (PMF) of skim milk was successfully used as a diafiltrant to remove SP from skim milk before cheese making, while maintaining the concentration of lactose, NPN, and nonmicellar calcium. About 95% of the SP originally in skim milk was removed by combining one 3 x MF stage and two 3 x PUF diafiltration stages. The final 3 x RMF can be diluted with PUF to the desired concentration of casein for traditional cheese making. The PMF from the skim milk was concentrated in a UF system to yield an SP concentrate with protein content similar to a whey protein concentrate, but without residuals from cheese making (i.e., rennet, culture, color, and lactic acid) that can produce undesirable functional and sensory characteristics in whey products. Additional processing steps to this 3-stage MF process for SP removal are discussed to produce an MF skim retentate for a continuous cottage cheese manufacturing process.     

Effect of manufacture and reconstitution of milk protein concentrate powder on the size and rennet gelation behaviour of casein micelles

Samples of raw skim milk, ultrafiltration/diafiltration retentate, concentrated retentate and milk protein concentrate powder (MPC80) from a single commercial production run were analysed using photon correlation spectroscopy. Measurements revealed insignificant differences in casein micelle size between the samples. In addition, there was no discernable difference between raw skim milk and MPC powder dissolved at 60 °C in the amount of casein remaining in supernatants from centrifugation at either 25,000 × g or 174,200 × g. Casein micelles did not appear to be altered during manufacture of MPC. The rennet gelation behaviour of reconstituted MPC was compared with raw skim milk. Reconstituted MPC did not coagulate unless supplemented with approximately 2 mm calcium chloride, which was attributed to the mineral removal during ultrafiltration/diafiltration. Addition of sufficient calcium could restore rennet coagulation kinetics and gel strength of reconstituted MPC to approximately that of raw skim milk.     

Yield and aging of Cheddar cheeses manufactured from milks with different milk serum protein contents

Whey proteins in general and specifically β-lactoglobulin, α-lactalbumin, and immunoglobulins have been thought to decrease proteolysis in cheeses manufactured from concentrated retentates from ultrafiltration. The proteins found in whey are called whey proteins and are called milk serum proteins (SP) when they are in milk. The experiment included 3 treatments; low milk SP (0.18%), control (0.52%), and high milk SP (0.63%), and was replicated 3 times. The standardized milk for cheese making of the low milk SP treatment contained more casein as a percentage of true protein and more calcium as a percentage of crude protein, whereas the nonprotein nitrogen and total calcium content was not different from the control and high SP treatments. The nonprotein nitrogen and total calcium content of the milks did not differ because of the process used to remove the milk SP from skim milk. The low milk SP milk contained less free fatty acids (FFA) than the control and high milk SP treatment; however, no differences in FFA content of the cheeses was detected. Approximately 40 to 45% of the FFA found in the milk before cheese making was lost into the whey during cheese making. Decreasing the milk SP content of milk by 65% and increasing the content by 21% did not significantly influence general Cheddar cheese composition. Higher fat recovery and cheese yield were detected in the low milk SP treatment cheeses. There was more proteolysis in the low milk SP cheese and this may be due to the lower concentration of undenatured β-lactoglobulin, α-lactalbumin, and other high molecular weight SP retained in the cheeses made from milk with low milk SP content.