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.     

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.     

Effect of denatured whey protein concentrate and its fractions on cheese composition and rheological properties

The objectives of this study were (1) to assess the effect of a denatured whey protein concentrate (DWPC) and its fractions on cheese yield, composition, and rheological properties, and (2) to separate the direct effect of the DWPC or its fractions on cheese rheological properties from the effect of a concomitant increase in cheese moisture. Semihard cheeses were produced at a laboratory scale, and mechanical properties were characterized by dynamic rheometry. Centrifugation was used to induce a moisture gradient in cheese to separate the direct contribution of the DWPC from the contribution of moisture to cheese mechanical properties. Cheese yield increased and complex modulus (G*) decreased when the DWPC was substituted for milk proteins in milk. For cheeses with the same moisture content, the substitution of denatured whey proteins for milk proteins had no direct effect on rheological parameters. The DWPC was fractionated to evaluate the contribution of its different components (sedimentable aggregates, soluble component, and diffusible component) to cheese yield, composition, and rheological properties. The sedimentable aggregates were primarily responsible for the increase in cheese yield when DWPC was added. Overall, moisture content explained to a large extent the variation in cheese rheological properties depending on the DWPC fraction. However, when the effect of moisture was removed, the addition of the DWPC sedimentable fraction to milk increased cheese complex modulus. Whey protein aggregates were hypothesized to act as active fillers that physically interact with the casein matrix and confer rigidity after pressing.     

Adjustment of vat milk treatment to optimize whey protein transfer into semi-hard cheese: A case study

The influence of heat treatment combined with microfiltration on the protein transfer from milk to cheese was investigated. Small-scale laboratory cheese-making experiments (10 L vat) showed that, upon adjusting coagulant and CaCl₂ addition, curd-making was possible as long as β-lactoglobulin denaturation was below 40%. It was also possible to compensate the negative effect of heating on rennet gel formation by protein enrichment through microfiltration. Depending on heat treatment intensity, the protein yield in curd increased to approximately 6%. Using Gouda cheese technology, pilot-scale experiments (500 L vat) showed that, depending on heat treatment intensity (up to 85 °C/60 s) and concentration (up to a concentration factor 2.0), it was possible to reduce the amount of protein which is lost in permeate and whey by 15–30%. Dry matter and crude protein of cheeses were significantly affected by heat treatment and microfiltration of milk, and proteolysis during maturation was delayed.     

Lactose recovery from Panela cheese whey: Effect of whey acidification on spontaneous and stirring-induced crystallisation

This work aimed to investigate the kinetics, yield, size and composition changes in lactose crystals when Panela cheese whey was acidified (pH 3.80) or slightly alkalinised (pH 6.89) before being subjected to spontaneous or stirring-induced crystallisation. At pH 3.8, the crystallisation was accelerated, and the incorporation of salts and proteins in lactose crystals decreased. Nevertheless, these conditions induced the formation of amorphous lactose. In contrast, at pH 6.89 and under stirring conditions, the amorphous lactose was not formed and gave a high crystallisation yield (∼25 g of lactose per Kg of whey) with ∼80% of lactose recovery.     

Functional properties of whey protein concentrate texturized at acidic pH: Effect of extrusion temperature

Reactive supercritical fluid extrusion (RSCFX) process at acidic condition (pH 3.0) was used to generate texturized whey protein concentrate (TWPC) and the impacts of process temperature on product's physicochemical properties were evaluated. TWPC extruded at 50 and 70 °C formed soft-textured aggregates with high solubility than that extruded at 90 °C that formed protein aggregates with low solubility. Total free sulfhydryl contents and solubility studies in selected buffers indicated that TWPC is primarily stabilized by non-covalent interactions. Proteins texturized at 90 °C showed an increased affinity for 1-anilino-naphthalene-8-sulfonate (ANS) and a decreased affinity for cis-parinaric acid (CPA), indicating changes in protein structure. Water dispersion of TWPC at room temperature showed thickening function with pseudoplastic behavior. Secondary gelation occurred in TWPC obtained at 50 and 70 °C by heating the cold-set gels to 95 °C. TWPC texturized at 90 °C produced cold-set gels with good thermal stability. Compared to control, TWPC formed stable oil-in-water emulsions. Factors such as degree of protein denaturation and the balance of surface hydrophobicity and solubility influenced the heat- and cold-gelation and emulsifying properties of the protein ingredients. TWPC generated by low and high temperature extrusions can thus be utilized for different products requiring targeted physicochemical functionalities.     

乳清浓缩蛋白在酸奶生产中的应用

以鲜奶，奶粉，乳清蛋白等乳成分为主要原料，研究了乳清浓缩蛋白在酸奶生产中的制做方法，对乳清浓缩蛋白代替部分高档脱脂奶粉生产酸奶产品的保水率，粘度，口感及组织状态进行了比较分析。结果表明，在酸奶生产中，添加一定的浓缩乳清蛋白代替高档脱脂奶粉是可行的，产品较为理想。     

High hydrostatic pressure modification of whey protein concentrate for improved functional properties

Whey protein concentrate (WPC) has many applications in the food industry. Previous research demonstrated that treatment of whey proteins with high hydrostatic pressure (HHP) can enhance solubility and foaming properties of whey proteins. The objective of this study was to use HHP to improve functional properties of fresh WPC, compared with functional properties of reconstituted commercial whey protein concentrate 35 (WPC 35) powder. Fluid whey was ultrafiltered to concentrate proteins and reconstituted to equivalent total solids (8.23%) as reconstituted commercial WPC 35 powder. Solutions of WPC were treated with 300 and 400 MPa (0- and 15-min holding time) and 600 MPa (0-min holding time) pressure. After HHP, the solubility of the WPC was determined at both pH 4.6 and 7.0 using UDY and BioRad protein assay methods. Overrun and foam stability were determined after protein dispersions were whipped for 15 min. The protein solubility was greater at pH 7.0 than at pH 4.6, but there were no significant differences at different HHP treatment conditions. The maintenance of protein solubility after HHP indicates that HHP-treated WPC might be appropriate for applications to food systems. Untreated WPC exhibited the smallest overrun percentage, whereas the largest percentage for overrun and foam stability was obtained for WPC treated at 300 MPa for 15 min. Additionally, HHP-WPC treated at 300 MPa for 15 min acquired larger overrun than commercial WPC 35. The HHP treatment of 300 MPa for 0 min did not improve foam stability of WPC. However, WPC treated at 300 or 400 MPa for 15 min and 600 MPa for 0 min exhibited significantly greater foam stability than commercial WPC 35. The HHP treatment was beneficial to enhance overrun and foam stability of WPC, showing promise for ice cream and whipping cream applications.     

Transglutaminase and hydroxypropyl methyl cellulose enhance mechanical properties of whey protein concentrate film

Whey protein and cellulose derivatives are abundant and renewable raw materials that provide an environmentally friendly alternative to fossil fuel sources used for food packaging. A novel biodegradable composite film comprising whey protein concentrates (WPC) aqueous solutions (10%, w/v) with different concentrations of Hydroxypropyl methylcellulose (HPMC) (0, 1, 2, 3, 4 and 5 wt% of WPC) was prepared in the present study. The effect of transglutaminase (TG) on the functional properties of the film was investigated. SDS-PAGE profiles indicated that TG modulated the formation of intermolecular cross-linking of WPC. FT-IR results showed that HPMC modified the mechanical properties of WPC. Incorporation of HPMC decreased the transparency and improved the tensile strength and extensibility of the film. TG addition led to a significant enhancement of the mechanical properties of the film. These findings indicated that TG promoted the formation of WPC-HPMC composite film with improved mechanical properties.     

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.     

Functional properties of chhana whey powders

The protein solubility, emulsifying, foaming and gelation properties, and viscosity of solutions of chhana whey protein powders, produced by ultrafiltration and reverse osmosis followed by drying, were studied over the pH range 2.5–9.0. Protein solubility varied from 57–100% and was greatest at low pH values. Chhana whey protein powders had similar emulsifying properties to commercial cheese whey protein powders of similar protein content, although the capacity to form gels when heated to 80°C was much lower, particularly at alkaline pH. the viscosity of solutions of the chhana whey powders was sensitive to pH, but was particularly high in the acidic range. These studies demonstrate considerable potential for the utilization of chhana whey, products in the food industry.     

The effect of bleaching agent on the flavor of liquid whey and whey protein concentrate

The increasing use and demand for whey protein as an ingredient requires a bland-tasting, neutral-colored final product. The bleaching of colored Cheddar whey is necessary to achieve this goal. Currently, hydrogen peroxide (HP) and benzoyl peroxide (BPO) are utilized for bleaching liquid whey before spray drying. There is no current information on the effect of the bleaching process on the flavor of spray-dried whey protein concentrate (WPC). The objective of this study was to characterize the effect of bleaching on the flavor of liquid and spray-dried Cheddar whey. Cheddar cheeses colored with water-soluble annatto were manufactured in duplicate. Four bleaching treatments (HP, 250 and 500 mg/kg and BPO, 10 and 20 mg/kg) were applied to liquid whey for 1.5 h at 60°C followed by cooling to 5°C. A control whey with no bleach was also evaluated. Flavor of the liquid wheys was evaluated by sensory and instrumental volatile analysis. One HP treatment and one BPO treatment were subsequently selected and incorporated into liquid whey along with an unbleached control that was processed into spray-dried WPC. These trials were conducted in triplicate. The WPC were evaluated by sensory and instrumental analyses as well as color and proximate analyses. The HP-bleached liquid whey and WPC contained higher concentrations of oxidation reaction products, including the compounds heptanal, hexanal, octanal, and nonanal, compared with unbleached or BPO-bleached liquid whey or WPC. The HP products were higher in overall oxidation products compared with BPO samples. The HP liquid whey and WPC were higher in fatty and cardboard flavors compared with the control or BPO samples. Hunter CIE Lab color values (L*, a*, b*) of WPC powders were distinct on all 3 color scale parameters, with HP-bleached WPC having the highest L* values. Hydrogen peroxide resulted in a whiter WPC and higher off-flavor intensities; however, there was no difference in norbixin recovery between HP and BPO. These results indicate that the bleaching of liquid whey may affect the flavor of WPC and that the type of bleaching agent used may affect WPC flavor.     

陶瓷膜超滤技术浓缩乳清的工艺参数研究

采用孔径为20nm的无机陶瓷膜超滤干酪副产物乳清,浓缩乳清蛋白。通过对膜过滤压力、温度以及乳清pH三个因素进行单因素分析以及正交实验优化,得到最佳工艺条件:操作压力0.25MPa,温度51℃,pH6.1,此条件下超滤膜渗透通量达到169.37L/m2.h,乳清蛋白可浓缩至5.4%,经喷雾干燥制得WPC蛋白质含量为38.2%。     

Studies on physicochemical and functional properties of commercial sweet whey powders

The objective of this study was to characterize variation and interrelatedness among primary functional and compositional parameters of commercially available sweet whey powders. Samples representing different plants/processes and cheese types were assayed for foaming capacity, foam stability, pH, protein content, soluble protein, turbidity, color, particle size distribution, lipid, and moisture. Data were analyzed using principal component analysis. Foaming capacity and stability varied from 10 to 220% and 0.1 to 14 min, respectively. Protein content and solubility ranged from 8.5 to 17.6% and 3.7 to 14.1%, respectively. Lipid content of sweet whey powder varied from 0.03 to 2.00%. The two main functional properties, foaming and protein solubility, did not show significant correlation with each other. Foaming properties showed a positive correlation to particle size and L* or lightness value, and negative correlation to lipid content. Protein solubility showed positive correlation with protein content and negative correlation with turbidity of the sample. Foaming behavior, protein, and particle size attributes were the main variables responsible for grouping of samples. Sweet whey powders from the same dairy plants were grouped together. The direct or indirect significance of these relationships to processing is detailed in this study.     

大豆乳清蛋白功能特性的研究

对经过膜分离技术提取的大豆乳清蛋白的功能特性进行研究。主要研究了pH对大豆乳清蛋白的溶解特性、起泡性能及乳化性能的影响,并对大豆乳清蛋白的组成成分进行了电泳分析。结果表明,大豆乳清蛋白具有较好的溶解性及起泡性,但泡沫稳定性及乳化性不如大豆分离蛋白。大豆乳清蛋白主要包含6种成分。     

Use of acid whey protein concentrate as an ingredient in nonfat cup set-style yogurt

Acid whey resulting from the production of soft cheeses is a disposal problem for the dairy industry. Few uses have been found for acid whey because of its high ash content, low pH, and high organic acid content. The objective of this study was to explore the potential of recovery of whey protein from cottage cheese acid whey for use in yogurt. Cottage cheese acid whey and Cheddar cheese whey were produced from standard cottage cheese and Cheddar cheese-making procedures, respectively. The whey was separated and pasteurized by high temperature, short time pasteurization and stored at 4°C. Food-grade ammonium hydroxide was used to neutralize the acid whey to a pH of 6.4. The whey was heated to 50°C and concentrated using ultrafiltration and diafiltration with 11 polyethersulfone cartridge membrane filters (10,000-kDa cutoff) to 25% total solids and 80% protein. Skim milk was concentrated to 6% total protein. Nonfat, unflavored set-style yogurts (6.0 ± 0.1% protein, 15 ± 1.0% solids) were made from skim milk with added acid whey protein concentrate, skim milk with added sweet whey protein concentrate, or skim milk concentrate. Yogurt mixes were standardized to lactose and fat of 6.50% and 0.10%, respectively. Yogurt was fermented at 43°C to pH 4.6 and stored at 4°C. The experiment was replicated in triplicate. Titratable acidity, pH, whey separation, color, and gel strength were measured weekly in yogurts through 8 wk. Trained panel profiling was conducted on 0, 14, 28, and 56 d. Fat-free yogurts produced with added neutralized fresh liquid acid whey protein concentrate had flavor attributes similar those with added fresh liquid sweet whey protein but had lower gel strength attributes, which translated to differences in trained panel texture attributes and lower consumer liking scores for fat-free yogurt made with added acid whey protein ingredient. Difference in pH was the main contributor to texture differences, as higher pH in acid whey protein yogurts changed gel structure formation and water-holding capacity of the yogurt gel. In a second part of the study, the yogurt mix was reformulated to address texture differences. The reformulated yogurt mix at 2% milkfat and using a lower level of sweet and acid whey ingredient performed at parity with control yogurts in consumer sensory trials. Fresh liquid acid whey protein concentrates from cottage cheese manufacture can be used as a liquid protein ingredient source for manufacture of yogurt in the same factory.