Permeation behaviour of buffalo milk Cheddar cheese whey during ultrafiltration

The permeation behaviour of buffalo-milk Cheddar cheese whey during ultrafiltration was studied. Buffalo-milk Cheddar cheese whey was adjusted to various pH levels ranging from 3.0 to 7.2 and ultrafiltration was carried out at 50° C to a level of 95% volume reduction by maintaining 1.75 and 0.50 bar inlet and outlet pressures, respectively. It was observed that the retentate had a minimum ash content of 3.17 % on a dry matter basis at pH 3.0 as against 6.23% when ultrafiltered at pH 7.2. As the pH was decreased from 7.2 to 3.0, the ash content of the retentate was drastically reduced. The calcium and phosphorus content of the retentate also varied significantly with change in pH, being minimal at pH 3.0 and increasing significantly with increase in pH of the whey. The yield of protein and lactose in the final retentate also varied with the pH of the whey. The permeate had a total solids content ranging from 5.65 to 5.78%. The maximal ash content of 0.59% was observed in the permeate when ultrafiltered at pH 3.0. As the whey pH increased, the ash content in the permeate decreased significantly. The total protein content of the permeate ranged from 0.18 to 0.23%. Most of the protein was observed to be non-protein nitrogen. Polyacrylamide gel electrophoresis showed the presence of-lactalbumin and traces of-lactoglobulin in the permeate. The lactose content of the permeate ranged from 4.98 to 5.02%. The results indicate that the final composition of whey protein concentrate can be altered by monitoring the volume reduction as well as by adjusting the whey pH before ultrafiltration.

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Das Permeationsverhalten von Molke aus Büffelmilch-Cheddar während der Ultrafiltration

Zusammenfassung Es wurde das Permeationsverhalten von Molke aus Büffelmilch-Cheddar während der Ultrafiltration studiert, und zwar bei verschiedenen pH-Werten von 3,0 bis 7,2 bei 50 °C mit einer Volumenreduktion von 95% bei 1,75 bzw. 0,50 Innen- bzw. Außendruck. Es wurde beobachtet, daß das Rententat eine minimale Trockensubstanz von 3,17% bei pH 3,0 gegenüber 6,23% bei pH 7,2 hatte. Durch die pH-Abnahme von 7,2 auf 3,0 wurde auch der Aschegehalt des Retentats drastisch reduziert. Der Ca- und P-Gehalt des Retentats variierte ebenfalls signifikant mit der pH-Veränderung, gleichfalls der Protein- und Lactose-Gehalt. Das Permeat hatte einen Gesamtgehalt von 5,65 bis 5,78%. Der maximale Aschegehalt von 0,59% wurde in dem bei pH 3,0 ultrafiltrierten Permeat festgestellt; der Aschegehalt nahm signifikant ab, wenn das pH der Molke zunahm. Der Proteingehalt des Permeaters lag zwischen 0,18 und 0,23%, wobei das meiste Nicht-Proteinstickstoff war. Polyacrylamidgelelektrophorese zeigte die Gegenwart von -Lactalbumin und Spuren-Lactglobulin im Permeat. Der Lactosegehalt rangierte von 4,98 bis 5,02%. Die Ergebnisse zeigen, daß die endgültige Zusammensetzung des Molkenkonzentrates sowohl durch die Volumenverringerung als auch durch die pH-Einstellung der Molke vor der Ultrafiltration eingestellt werden kann.

     

Compositional and physical properties of yogurts manufactured from milk and whey cheese concentrated by ultrafiltration

Yogurts made with 80% milk retentate (MR) [Volume Reduction Factor (VRF) = 1.5] and 20% cheese whey retentate (WR; VRF = 8.0) (yogurt 1) and yogurts made with 100% MR through ultrafiltration have been evaluated as to flow, texture profile analysis (TPA) and syneresis index. As with MR and WR, their physico‐chemical composition was also determined. The yogurt to which WR had been added showed; less apparent viscosity and greater tixotrophya; less firmness and adhesiveness and greater cohesiveness; higher syneresis index, less protein and mineral content, and greater lipid content in comparison with the yogurt made only with MR.     

Manufacture of Cheddar cheese from high-pressure-treated whole milk

The cheese-making characteristics of high-pressure (HP)-treated milk were examined. The rennet coagulation time of pasteurised milk decreased after HP treatment at 400 MPa but increased after treatment at 600 MPa. The L-value (whiteness) of milk decreased directly after HP treatment but, over the course of coagulation, whiteness of HP-treated milk increased to the same level as in the control. Cheddar cheese was then manufactured from raw whole milk or whole milk treated by high-pressure (HP) at 400 MPa (HP400) or 600 MPa (HP600) for 10 min at 20 °C. HP treatment of raw milk at 600 MPa resulted in a 3.66 log reduction in the initial counts of non-starter lactic acid bacteria (NSLAB), decreased protein and fat content, as well as a lower pH compared to the control. Furthermore, higher treatment pressures resulted in increased incorporation of β-lactoglobulin into the cheese curd, with parallel increases in yield by 1.23% and 7.78% for HP400 and HP600 cheeses, respectively. Overall, this study showed that the effects of HP treatment on milk proteins increased rennet coagulation times and changes in cheese composition at day 1.Industrial relevanceHigh-pressure treatment is a novel technology which has been applied to a number of commercial food products. In this study, HP-induced changes in milk proteins resulted in increased cheese yields and increased cheese whiteness. In addition, HP treatment significantly reduced the microflora of raw milk cheese. Those attributes could be of interest for both industry and consumer.     

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.     

Use of dry milk protein concentrate in pizza cheese manufactured by culture or direct acidification

Milk protein concentrate (MPC) contains high concentrations of casein and calcium and low concentrations of lactose. Enrichment of cheese milk with MPC should, therefore, enhance yields and improve quality. The objectives of this study were: 1) to compare pizza cheese made by culture acidification using standardized whole milk (WM) plus skim milk (SM) versus WM plus MPC; and 2) compare cheese made using WM + MPC by culture acidification to that made by direct acidification. The experimental design is as follows: vat 1 = WM + SM + culture (commercial thermophilic lactic acid bacteria), vat 2 = WM + MPC + culture, and vat 3 = WM + MPC + direct acid (2% citric acid). Each cheese milk was standardized to a protein-to-fat ratio of approximately 1.4. The experiment was repeated three times. Yield and composition of cheeses were determined by standard methods, whereas the proteolysis was assessed by urea polyacrylamide gel electrophoresis (PAGE) and water-soluble N contents. Meltability of the cheeses was determined during 1 mo of storage, in addition to pizza making. The addition of MPC improved the yields from 10.34 +/- 0.57% in vat 1 cheese to 14.50 +/- 0.84% and 16.65 +/- 2.23%, respectively, in vats 2 and 3 and cheeses. The percentage of fat and protein recoveries showed insignificant differences between the treatments, but TS recoveries were in the order, vat 2 > vat 3 > vat 1. Most of the compositional parameters were significantly affected by the different treatments. Vat 2 cheese had the highest calcium and lowest lactose contencentrations. Vat 3 cheese had the best meltability. Vat 1 cheese initially had better meltability than vat 2 cheese; however, the difference became insignificant after 28 d of storage at 4 degrees C. Vat 3 cheese had the softest texture and produced large-sized blisters when baked on pizza. The lowest and highest levels of proteolysis were found in vats 2 and 3 cheeses, respectively. The study demonstrates the use of MPC in pizza cheese manufacture with improved yield both by culture acidification as well as direct acidification.     

Reduced fat process cheese made from young reduced fat Cheddar cheese manufactured with exopolysaccharide-producing cultures

In a previous study, exopolysaccharide (EPS)-producing cultures improved textural and functional properties of reduced fat Cheddar cheese. Because base cheese has an impact on the characteristics of process cheese, we hypothesized that the use of EPS-producing cultures in making base reduced fat Cheddar cheese (BRFCC) would allow utilization of more young cheeses in making reduced fat process cheese. The objective of this study was to evaluate characteristics of reduced fat process cheese made from young BRFCC containing EPS as compared with those in cheese made from a 50/50 blend of young and aged EPS-negative cheeses. Reduced fat process cheeses were manufactured using young (2 d) or 1-mo-old EPS-positive or negative BRFCC. Moisture and fat of reduced fat process cheese were standardized to 49 and 21%, respectively. Enzyme modified cheese was incorporated to provide flavor of aged cheese. Exopolysaccharide-positive reduced fat process cheese was softer, less chewy and gummy, and exhibited lower viscoelastic moduli than the EPS-negative cheeses. The hardness, chewiness, and viscoelastic moduli were lower in reduced fat process cheeses made from 1-mo-old BRFCC than in the corresponding cheeses made from 2-d-old BRFCC. This could be because of more extensive proteolysis and lower pH in the former cheeses. Sensory scores for texture of EPS-positive reduced fat process cheeses were higher than those of the EPS-negative cheeses. Panelists did not detect differences in flavor between cheeses made with enzyme modified cheese and aged cheese. No correlations were found between the physical and melting properties of base cheese and process cheese.     

Permeate from cheese whey ultrafiltration is a source of milk oligosaccharides

Previously undescribed oligosaccharides in bovine cheese whey permeate were characterized by a combination of nanoelectrospray Fourier transform ion cyclotron resonance (nESI-FTICR) mass spectrometry and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance (MALDI-FTICR) mass spectrometry. Oligosaccharide composition was elucidated by collision-induced dissociation within the ICR cell. In addition to sialyllactose (the most abundant oligosaccharide in bovine colostrum), we identified 14 other oligosaccharides, half of which have the same composition of human milk oligosaccharides. These oligosaccharides could potentially be used as additives in infant formula and products for the pharmaceutical industry. Because whey permeate is a by-product from the production of whey protein concentrate (WPC) and is readily available, it is an attractive source of oligosaccharides for potential application in human nutrition.     

Hard ewe's milk cheese manufactured from milk of three different groups of somatic cell counts

As ovine milk production increases in the United States, somatic cell count (SCC) is increasingly used in routine ovine milk testing procedures as an indicator of flock health. Ovine milk was collected from 72 East Friesian-crossbred ewes that were machine milked twice daily. The milk was segregated and categorized into three different SCC groups: < 100,000 (group I); 100,000 to 1,000,000 (group II); and > 1,000,000 cells/ ml (group III). Milk was stored frozen at -19 degrees C for 4 mo. Milk was then thawed at 7 degrees C over a 3-d period before pasteurization and cheese making. Casein (CN) content and CN-to-true protein ratio decreased with increasing SCC group 3.99, 3.97, to 3.72% CN, and 81.43, 79.72, and 79.32% CN to true protein ratio, respectively. Milk fat varied from 5.49, 5.67, and 4.86% in groups I, II, and III, respectively. Hard ewe's milk cheese was made from each of the three different SCC groups using a Manchego cheese manufacturing protocol. As the level of SCC increased, the time required for visual flocculation increased, and it took longer to reach the desired firmness for cutting the coagulum. The fat and moisture contents were lower in the highest SCC cheeses. After 3 mo, total free fatty acids (FFA) contents were significantly higher in the highest SCC cheeses. Butyric and caprylic acids levels were significantly higher in group III cheeses at all stages of ripening. Cheese graders noted rancid or lipase flavor in the highest SCC level cheeses at each of the sampling points, and they also deducted points for more body and textural defects in these cheeses at 6 and 9 mo.     

凝乳酶对超滤浓缩乳生产Quark干酪的影响

采用每100g超滤乳中添加0、50、100、150、200、250μL六个水平的凝乳酶,研究了不同的凝乳酶添加量对Quark干酪组成、凝乳硬度、贮藏期产品感官品质和干酪中水溶性氮含量的影响。结果表明,当凝乳酶的添加量从0μL/100g增大到250μL/100g时,产品的水分含量上升了1·49%,粗产率和校正产率分别上升了1·42%和0·99%,固形物的回收率下降了3·5%,凝乳硬度从16·83g增大到40·84g,但干酪的苦味和水溶性氮含量,随着贮存期的延长和凝乳酶用量的增加而增大。      

A comparison of the quality of Cheddar cheese produced from seasonal and standardized milk

The quality of Cheddar cheese made from seasonal and standardized milk has been assessed over a 12-month period. There was a slight consumer preference for cheese made from seasonal milk, but the difference was small and unlikely to be of commercial significance. Grade scores for cheese 'body' were not reflected in a consumer taste panel assessment of the quality of the mature cheese.     

Characteristics of reduced fat Cheddar cheese made from ultrafiltered milk with an exopolysaccharide-producing culture

In a previous study, ultrafiltration (UF) at 1.2x reduced residual chymosin activity and bitterness in exopolysaccharide (EPS)-positive reduced fat Cheddar cheese. The objective of this research was to study the effect of this level of concentration on the textural and functional characteristics of the reduced fat cheese. Ultrafiltration (1.2x) did not affect the hardness, cohesiveness, adhesiveness, chewiness, and gumminess of EPS-positive cheese. The 6-month old UF cheeses were springier than non-UF cheeses. However, the springiness of the EPS-positive cheese made from UF milk was much lower than that of the EPS-negative cheeses. Texture of the EPS-negative cheese was more affected by UF than that of the EPS-positive cheese. Differences were seen in the extent of flow between UF and non-UF cheeses at 1 and 3-months but not after 6 months ripening. Ultrafiltration increased the elastic modulus in the 6-month old EPS-positive cheeses. Higher body and texture scores were given to EPS-positive cheeses than the EPS-negative ones. Sensory panelists found the body of the UF and non-UF cheeses to be similar.     

双蛋白切达干酪成熟过程中的质构和感官评价分析

在原料乳中添加质量分数为10%豆乳进行切达干酪加工,研究成熟过程中豆蛋白和筛选发酵剂对干酪质构及感官影响。结果表明,豆乳和发酵剂对干酪的基础理化指标有显著影响,从干酪质构分析结果可以看出,干酪在成熟期间,豆乳的添加对干酪的硬度、弹性、黏聚性和咀嚼性都有显著影响,干酪硬度和咀嚼度下降。应用发酵剂L.Lactis subsp.Cremoris QH27-1和L.Lactis subsp.LactisXZ3303生产双蛋白切达干酪可以提高干酪的质构特征和感官品质。     

Effects of protein and fat levels in milk on Cheddar cheese yield

Over a 14-month period, bulk tank milk was collected twice a week and was adjusted with cream and skim milk powder to provide six levels each of fat and protein varying from 3·0 to 4·0%. Milk samples were analyzed for total solids, fat, protein, casein, lactose and somatic cell count and were used for laboratory-scale cheesemaking. Data obtained from the milk input and the cheese output were used to determine actual, moisture adjusted, theoretical yield, and efficiency of yield. Least squares analyses of data indicated that higher cheese yields were obtained from higher fat and protein contents in milk. Higher yield efficiency was associated with higher ratios of protein to fat and casein to fat. Regression analysis indicated that a percentage increase in fat content in milk resulted in an increase of 1·23–1·37% in moisture adjusted yield in the different protein levels. For a similar increase of protein in milk, there were 1·80–2·04% increase in moisture adjusted yields in different fat levels.     

Utilization of microfiltration or lactoperoxidase system or both for manufacture of Cheddar cheese from raw milk

The objective of the present study was to determine if application of microfiltration (MF) or raw milk lactoperoxidase system (LP) could reduce the risk of foodborne illness from Escherichia coli in raw milk cheeses, without adversely affecting the overall sensory acceptability of the cheeses. Escherichia coli K12 was added to raw milk to study its survival as a non-pathogenic surrogate organism for pathogenic E. coli. Five replications of 6 treatments of Cheddar cheese were manufactured. The 6 treatments included cheeses made from pasteurized milk (PM), raw milk (RM), raw milk inoculated with E. coli K12 (RME), raw milk inoculated with E. coli K12 + LP activation (RMELP), raw milk inoculated with E. coli K12 + MF (MFE), and raw milk inoculated with E. coli K12 + MF + LP activation (MFELP). The population of E. coli K12 was enumerated in the cheese milks, in whey/curds during cheese manufacture, and in final Cheddar cheeses during ripening. Application of LP, MF, and a combination of MF and LP led to an average percentage reduction of E. coli K12 counts in cheese milk by 72, 88, and 96%, respectively. However, E. coli K12 populations significantly increased during the manufacture of Cheddar cheese for the reasons not related to contamination. The number of E. coli K12, however, decreased by 1.5 to 2 log cycles during 120 d of ripening, irrespective of the treatments. The results suggest that MF with or without LP significantly lowers E. coli count in raw milk. Hence, if reactivation of E. coli during cheese making could be prevented, MF with or without LP would be an effective technique for reducing the counts of E. coli in raw milk cheeses. The cheeses were also analyzed for proteolysis, starter and nonstarter lactic acid bacteria (NSLAB), and sensory characteristics during ripening. The concentration of pH 4.6 soluble nitrogen at 120 d was greater in PM cheese compared with the other treatments. The level of 12% trichloroacetic acid-soluble nitrogen at 120 d was greater in RM, RME, and RMELP cheeses compared with PM, MFE, and MFELP cheeses. This could be related to the fact that cheeses made from raw milk with or without LP (RM, RME, and RMELP) had greater levels of NSLAB compared with PM, MFE, and MFELP cheeses. Cheeses at 60 d, as evaluated by 8 trained panelists, did not differ in bitterness, pastiness, or curdiness attributes. Cheeses at 120 d showed no differences in acid-taste, bitterness, or curdiness attributes. Sensory analysis at 60 d showed that PM and MFELP cheeses had greater overall sensory acceptability than RM and RME cheeses. The overall sensory acceptability of the cheeses at 120 d showed that PM, MFE, and MFELP cheeses were more acceptable than RM and RME cheeses.     

Proteomic study of proteolysis during ripening of Cheddar cheese made from milk over a lactation cycle

Milk for cheese production in Ireland is predominantly produced by pasture-fed spring-calving herds. Consequently, there are marked seasonal changes in milk composition, which arise from the interactive lactational, dietary and environmental factors. In this study, Cheddar cheese was manufactured on a laboratory scale from milk taken from a spring calving herd, over a 9-month lactation cycle between early April and early December. Plasmin activity of 6-months-old Cheddar cheese samples generally decreased over ripening time. One-dimensional urea-polyacrylamide gel electrophoresis (PAGE) of cheese samples taken after 6 months of ripening showed an extensive hydrolysis of caseins, with the fastest hydrolysis of α(s1)-caseins in cheeses made in August. A proteomic comparison between cheeses produced from milk taken in April, August and December showed a reduction in levels of β-casein and appearance of additional products, corresponding to low molecular weight hydrolysis products of the caseins. This study has demonstrated that a seasonal milk supply causes compositional differences in Cheddar cheese, and that proteomic tools are helpful in understanding the impact of those differences.     

Effect of proteolysis during Cheddar cheese aging on the detection of milk protein residues by ELISA

Cow milk is a common allergenic food, and cow milk-derived cheese retains an appreciable level of allergenicity. The specific and sensitive detection of milk protein residues in foods is needed to protect milk-allergic consumers from exposure to undeclared milk protein residues contained in foods made with milk or milk-derived ingredients or made on shared equipment or in shared facilities with milk or milk-derived ingredients. However, during cheese ripening, milk proteins are degraded by chymosin and milk-derived and bacterial proteases. Commercial allergen-detection methods are not validated for the detection of residues in fermented or hydrolyzed products. The objective of this research was to evaluate commercially available milk ELISA kits for their capability to detect milk protein residues in aged Cheddar cheese. Cheddar cheese was manufactured at a local dairy plant and was aged at 5°C for 24 mo, with samples removed at various time points throughout aging. Milk protein residues and protein profiles were measured using 4 commercial milk ELISA kits and sodium dodecyl sulfate-PAGE. The ELISA data revealed a 90% loss of milk protein residue signal between the youngest and oldest Cheddar cheese samples (0.5 and 24 mo, respectively). Sodium dodecyl sulfate-PAGE analysis showed protein degradation throughout aging, with the highest level of proteolysis observed at 24 mo. Results suggest that current commercial milk ELISA methods can detect milk protein residues in young Cheddar cheese, but the detection signal dramatically decreases during aging. The 4 evaluated ELISA kits were not capable of detecting trace levels of milk protein residues in aged cheese. Reliable detection of allergen residues in fermented food products is critical for upholding allergen-control programs, maintaining product safety, and protecting allergic consumers. Furthermore, this research suggests a novel use of ELISA kits to monitor protein degradation as an indication of cheese ripening.     

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.