Production of a high gel strength whey protein concentrate from cheese whey

In order to develop a process for the production of a whey protein concentrate (WPC) with high gel strength and water-holding capacity from cheese whey, we analyzed 10 commercially available WPC with different functional properties. Protein composition and modification were analyzed using electrophoresis, HPLC, and mass spectrometry. The analyses of the WPC revealed that the factors closely associated with gel strength and water-holding capacity were solubility and composition of the protein and the ionic environment. To maintain whey protein solubility, it is necessary to minimize heat exposure of the whey during pretreatment and processing. The presence of the caseinomacropeptide (CMP) in the WPC was found to be detrimental to gel strength and water-holding capacity. All of the commercial WPC that produced high-strength gels exhibited ionic compositions that were consistent with acidic processing to remove divalent cations with subsequent neutralization with sodium hydroxide. We have shown that ultrafiltration/diafiltration of cheese whey, adjusted to pH 2.5, through a membrane with a nominal molecular weight cut-off of 30,000 at 15 degrees C substantially reduced the level of CMP, lactose, and minerals in the whey with retention of the whey proteins. The resulting WPC formed from this process was suitable for the inclusion of sodium polyphosphate to produce superior functional properties in terms of gelation and water-holding capacity.     

Effect of anthocyanin-absorbed whey protein microgels on physicochemical and textural properties of reduced-fat Cheddar cheese

Reduced-fat foods have become more popular due to their health benefits; however, reducing the fat content of food affects the sensory experience. Therefore, it is necessary to improve the sensory acceptance of reduced-fat foods to that of full-fat equivalents. The aim of this study was to evaluate the effect of adding whey protein microgels (WPM) with an average diameter of 4 μm, or WPM with adsorbed anthocyanins [WPM (Ant)] on the textural and sensory properties of reduced-fat Cheddar cheese (RFC). Reduced-fat Cheddar cheese was prepared in 2 ways: (1) by adding WPM, designated as RFC+M, or (2) by adding WPM (Ant), designated as RFC+M (Ant). For comparison, RFC without fat substitutes and full-fat Cheddar cheese were also prepared. We discovered that the addition of WPM and WPM (Ant) increased the moisture content, fluidity, and meltability of RFC, and reduced its hardness, springiness, and chewiness. The textural and sensory characteristics of RFC were markedly inferior to those of full-fat Cheddar cheese, whereas addition of WPM and WPM (Ant) significantly improved the sensory characteristics of RFC. The WPM and WPM (Ant) showed a high potential as fat substitutes and anthocyanin carriers to effectively improve the acceptance of reduced-fat foods.     

Improvement of low fat mozzarella cheese properties using denatured whey protein

Mozzarella cheese was made from buffalo milk (6% fat) or from partially skimmed buffalo milk (2 and 4% fat) with 0.5 and 1% denatured whey protein. Adding whey protein to buffalo milk decreased rennet coagulation time and curd tension whereas increased curd synaeresis. Addition of whey protein to cheese milk increased the acidity, total solids, ash, salt, salt in moisture, also some nitrogen fractions. The meltability and oiling‐off values increased but the calcium values of mozzarella cheese decreased. The sensory properties of low fat mozzarella cheese were improved by addition of whey protein to the cheese milk.     

Functional properties of native and cheese whey protein concentrate powders

The objective of this study was to compare microfiltered native whey protein concentrate and traditional cheese whey protein concentrate powders and their functional properties. Solubility, viscosity, gelation, foaming properties, emulsification and water-holding capacity were studied. The effect of spray and freeze drying methods on functional properties was evaluated. Gel strength varied from 0.11 to 0.65 N. Foaming stability and overrun varied from 0 to 29.3 min and from 230 to 2200%, respectively. Foaming and gelation properties were clearly better with native whey protein powders. Differences between drying methods were not observed but higher heat load decreased solubility.     

Effect of substituting whey cream for sweet cream on the textural and rheological properties of cream cheese

In the manufacture of cream cheese, sweet cream and milk are blended to prepare the cream cheese mix, although other ingredients such as condensed skim milk and skim milk powder may also be included. Whey cream (WC) is an underutilized fat source, which has smaller fat droplets and slightly different chemical composition than sweet cream. This study investigated the rheological and textural properties of cream cheeses manufactured by substituting sweet cream with various levels of WC. Three different cream cheese mixes were prepared: control mix (CC; 0% WC), cream cheese mixes containing 25% WC (25WC; i.e., 75% sweet cream), and cream cheese mixes with 75% WC (75WC; i.e., 25% sweet cream). The CC, 25WC, and 75WC mixes were then used to manufacture cream cheeses. We also studied the effect of WC on the initial step in cream cheese manufacture (i.e., the acid gelation process monitored using dynamic small amplitude rheology). Acid gels were also prepared with added denatured whey proteins or membrane proteins/phospholipids (PL) to evaluate how these components affected gel properties. The rheological, textural, and sensory properties of cream cheeses were also measured. The WC samples had significantly higher levels of PL and insoluble protein compared with sweet cream. An increase in the level of WC reduced the rate of acid gel development, similar to the effect of whey phospholipid concentrate added to mixes. In cream cheese, an increase in the level of added WC resulted in significantly lower storage modulus values at temperatures <20°C. Texture results, obtained from instrumental and sensory analyses, showed that high level of WC resulted in significantly lower firmness or hardness values and higher stickiness compared with cream cheeses made with 25WC or CC cream cheeses. The softer, less elastic gels or cheeses resulting from the use of high levels of WC are likely due to the presence of components such as PL and proteins from the native milk fat globule membrane. The use of low levels of WC in cream cheese did not alter the texture, whereas high levels of WC could be used if manufacturers want to produce more spreadable products.     

Effect of whey concentration on protein recovery in fresh ovine ricotta cheese

Ricotta cheese, particularly the ovine type, is a typical Italian dairy product obtained by heat-coagulation of the proteins in whey. The aim of this work was to investigate the influence of whey protein concentration, obtained by ultrafiltration, on yield of fresh ovine ricotta cheese. Ricotta cheeses were obtained by thermocoagulation of mixtures with protein content of 1.56, 3.10, 4.16, and 7.09 g/100 g from the mixing of skim whey and ultrafiltered skim whey. A fat-to-protein ratio of 1.1 (wt/wt) was obtained for all mixtures by adding fresh cream. The initial mixtures, as well as the final ricotta cheeses, were analyzed for their composition and by SDS-PAGE. Protein bands were quantified by QuantityOne software (Bio-Rad, Hercules, CA) and identified by liquid chromatography-tandem mass spectrometry. Significant differences in the composition of the ricotta cheese were observed depending on protein concentration. Particularly, ricotta cheese resulting from the mixture containing 7.09 g/100 g of protein presented higher moisture (72.88 ± 1.50 g/100 g) and protein (10.18 ± 0.45 g/100 g) contents than that prepared from the mixture with 1.56 g/100 g of protein (69.52 ± 1.75 and 6.70 ± 0.85 g/100 g, respectively), and fat content was lower in this sample (12.20 ± 1.60 g/100 g) compared with the other treatments, with mean values between 15.72 and 20.50 g/100 g. Each protein fraction presented a different behavior during thermocoagulation. In particular, the recovery of β-lactoglobulin and α-lactalbumin in the cheese increased as their content increased in the mixtures. It was concluded that concentrating ovine rennet whey improved the extent of heat-induced protein aggregation during the thermal coagulation process. This resulted in a better recovery of each protein fraction in the product, and in a consequent increase of ricotta cheese yield.     

Effect of denatured whey protein concentrate and its fractions on rennet-induced milk gels

Denatured whey protein concentrate was fractionated by centrifugation to study the effect of its different components (sedimentable aggregates, non-sedimentable component, and diffusible component) on rennet-induced coagulation of milk and gel contraction capacity. Milk coagulation properties were characterized by optical density measurement and dynamic rheometry. The contraction kinetics of the gel during cooking was also characterized. The diffusible component of denatured whey protein concentrate showed no significant effect on coagulation or contraction parameters. Sedimentable aggregates negatively influenced the kinetics of rennet gel formation, as measured by rheology; these aggregates also reduced the contraction capacity of the gel. The non-sedimentable component negatively influenced milk coagulation properties, as measured with both optical and rheological methods, and decreased the contraction capacity of the gel. The results suggest that, beyond the effect of sedimentable whey protein aggregates, soluble proteinaceous complexes (non-sedimentable and non-diffusible) could interact with renneted casein micelles and limit gel formation and contraction.     

酪蛋白与乳清蛋白比例对酸奶凝胶性质的影响

研究了乳中酪蛋白和乳清蛋白比例对凝固型酸奶流变学特性和微观结构的影响,结果表明,固定蛋白质质量分数、降低酪蛋白和乳清蛋白的比例,可以明显提高酸奶凝胶的质量.乳中蛋白质质量分数一致时,酸奶凝胶的硬度、黏度、持水力随着酪蛋白和乳清蛋白比例的减小而增大,凝胶网络结构变得更规则、致密,孔隙更小.在低蛋白质质量分数下,降低乳中酪...     

Effects of protein and fat levels in milk on cheese and whey compositions

Bulk tank milk was standardised to six levels of fat (3·0, 3·2, 3·4, 3·6, 3·8, 4·0%) and similarly to six levels of protein, thus giving a total of 36 combinations in composition. Milk was analyzed for total solids, fat, protein, casein, lactose and somatic cell count and was used to make laboratory-scale cheese. Cheese samples from each batch were assayed for total solids, fat, protein and salt. Losses of milk components in the whey were also determined. Least squares analysis of data indicated that higher protein level in milk was associated with higher protein and lower fat contents in cheese. This was accompanied by lower total solids (higher moisture) in cheese. Inversely, higher fat level in milk gave higher fat and lower protein and moisture contents in cheese. Higher fat level in milk resulted in lower retention of fat in cheese and more fat losses in the whey. Higher protein level in milk gave higher fat retention in cheese and less fat losses in the whey. Regression analysis showed that cheese fat increased by 4·22%, while cheese protein decreased by 2·61% for every percentage increase in milk fat. Cheese protein increased by 2·35%, while cheese fat decreased by 6·14% per percentage increase in milk protein. Milk with protein to fat ratio close to 0·9 would produce a minimum of 50% fat in the dry matter of cheese.     

Use of microparticulated whey protein concentrate,exopolysaccharide-producing Streptococcus thermophilus, and adjunct cultures for making low-fat Italian Caciotta-type cheese

Low-fat Caciotta-type cheeses were manufactured with partially skim milk (fat content of ~0.3%) alone (LFC); with the supplementation of 0.5% (wt/vol) microparticulated whey protein concentrate (MWPC) (LFC-MWPC); with MWPC and exopolysaccharides (EPS)-producing Streptococcus thermophilus ST446 (LFC-MWPC-EPS); and with MWPC, EPS-producing strain ST446, and Lactobacillus plantarum LP and Lactobacillus rhamnosus LRA as adjunct cultures (LFC-MWPC-EPS-A). The non-EPS-producing isogenic variant Streptococcus thermophilus ST042 was used for making full-fat Caciotta-type cheese (FFC), LFC, and LFC-MWPC. Cheeses were characterized based on compositional, microbiological, biochemical, texture, volatile components (purge and trap, and solid-phase microextraction coupled with gas chromatography-mass spectrometry), and sensory analyses. Compared with FFC and LFC (51.6 ± 0.7 to 53.0 ± 0.9%), the other cheese variants retained higher levels of moisture (60.5 ± 1.1 to 67.5 ± 0.5%). The MWPC mainly contributed to moisture retention. Overall, all LFC had approximately one-fourth (22.6 ± 0.8%) of the fat of FFC. Hardness of cheeses slightly varied over 7 d of ripening. Microbial EPS positively affected cheese texture, and the texture of LFC without MWPC or microbial EPS was excessively firm. Free amino acids were at the highest levels in LFC treatments (2,705.8 ± 122 to 3,070.4 ± 123 mg/kg) due to the addition of MWPC and the peptidase activity of adjunct cultures. Aldehydes, alcohols, ketones, sulfur compounds, and short- to medium-chain carboxylic acids differentiated LFC variants and FFC. The sensory attributes pleasant to taste, intensity of flavor, overall acceptability, and pleasant to chew variously described LFC-MWPC-EPS and LFC-MWPC-EPS-A. Based on the technology options used, low-fat Caciotta-type cheese (especially ripened for 14 d) has promising features to be further exploited as a suitable alternative to the full-fat variant.     

工艺参数对再制干酪的质构和流变性质的影响

利用质构仪和流变仪对影响再制干酪品质的多个因素进行了研究。结果表明，水分影响再制干酪的质构和流变性质：乳化盐对再制干酪产品的质构没有显著的影响；不同的温度和不同的搅拌时间对样品的质构有着相似的变化；在所有加工条件下．再制干酪的G′始终大于G″，G′和G″没有交叉点，而且复合黏度η^＊随着频率的增加而急剧降低，体系表现出了弱凝胶的特性。     

Production of low antigenic cheese whey protein hydrolysates using mixed proteolytic enzymes

This study examined the effect of different proteolytic enzymes on the production of cheese whey protein (CWP) hydrolysates with low antigenicity. Four enzyme combinations (1:1) trypsin + papain W‐40 (TP), trypsin + neutrase 1.5 (TN), papain W‐40 + protease S (PP) and papain W‐40 + neutrase 1.5 (PN) were added at the rate of 1% of the CWP and it was incubated for 15, 30, 60, 90, 120 and 180 min at 50 °C. CWP hydrolysis and its non‐protein nitrogen concentrations were higher with TP and TN compared with PP and PN at all incubation times. The SDS‐PAGE revealed complete removal of α‐lactalbumin (α‐LA) and β‐lactoglobulin (β‐LG) from hydrolysates produced by trypsin‐containing enzyme mixtures. Reverse‐phase HPLC analysis ascertained the CWP hydrolysis and SDS‐PAGE results. The lowest antigenicity in CWP hydrolysates was observed with the use of trypsin‐containing enzyme mixtures compared with other enzyme combinations. Present results suggested that TP and TN combinations were the most effective for CWP hydrolysis for the removal of β‐LG from CWP. Further research is warranted to identify the peptides in CWP hydrolysates produced with these enzyme combinations that may help enhance the utilisation of whey protein in human food. Copyright © 2007 Society of Chemical Industry     

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.     

Functional properties of biscuits with whey protein concentrate and honey

The effects of honey, lemon juice, and two different whey protein concentrates (WPC) on the structural and functional properties of biscuits, were analysed. Firmness, elasticity, relaxation time, adhesiveness, consistency and cohesiveness of dough and colour, fracture stress and fracture strain of biscuits were also determined. The presence of WPC with a high protein content produced a decrease in the firmness and consistency and an increase in the cohesiveness of dough. Honey increased the adhesiveness of dough, mainly in samples with the WPC of lower protein content and lemon juice, and tended to decrease dough relaxation time. The fracture stress of biscuits decreased with the incorporation of WPC. Also, honey increased the red undertone and yellowness of biscuits and decreased their lightness; however, the addition of lemon juice reduced these effects.