Efficiency of removal of whey protein from sweet whey using polymeric microfiltration membranes

Our objective was to measure whey protein removal percentage from separated sweet whey using spiral-wound (SW) polymeric microfiltration (MF) membranes using a 3-stage, 3× process at 50°C and to compare the performance of polymeric membranes with ceramic membranes. Pasteurized, separated Cheddar cheese whey (1,080 kg) was microfiltered using a polymeric 0.3-μm polyvinylidene (PVDF) fluoride SW membrane and a 3×, 3-stage MF process. Cheese making and whey processing were replicated 3 times. There was no detectable level of lactoferrin and no intact α- or β-casein detected in the MF permeate from the 0.3-μm SW PVDF membranes used in this study. We found BSA and IgG in both the retentate and permeate. The β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) partitioned between retentate and permeate, but β-LG passage through the membrane was retarded more than α-LA because the ratio of β-LG to α-LA was higher in the MF retentate than either in the sweet whey feed or the MF permeate. About 69% of the crude protein present in the pasteurized separated sweet whey was removed using a 3×, 3-stage, 0.3-μm SW PVDF MF process at 50°C compared with 0.1-μm ceramic graded permeability MF that removed about 85% of crude protein from sweet whey. The polymeric SW membranes used in this study achieve approximately 20% lower yield of whey protein isolate (WPI) and a 50% higher yield of whey protein phospholipid concentrate (WPPC) under the same MF processing conditions as ceramic MF membranes used in the comparison study. Total gross revenue from the sale of WPI plus WPPC produced with polymeric versus ceramic membranes is influenced by both the absolute market price for each product and the ratio of market price of these 2 products. The combination of the market price of WPPC versus WPI and the influence of difference in yield of WPPC and WPI produced with polymeric versus ceramic membranes yielded a price ratio of WPPC versus WPI of 0.556 as the cross over point that determined which membrane type achieves higher total gross revenue return from production of these 2 products from separated sweet whey. A complete economic engineering study comparison of the WPI and WPPC manufacturing costs for polymeric versus ceramic MF membranes is needed to determine the effect of membrane material selection on long-term processing costs, which will affect net revenue and profit when the same quantity of sweet whey is processed under various market price conditions.     

ADSA Foundation Scholar Award: defining dairy flavors

Production and consumption of dairy foods continue to increase annually. Further, new ingredient applications for dairy foods continue to expand. With continued production and consumption, there is also increased competition. Increased competition exists regionally, nationally, and globally. Processors as well as product developers must find ways to maximize existing markets and expand into new markets. A consistent high quality product is necessary to maintain competitiveness. Although microbial safety and stability are key ways to define quality, flavor is one method of defining quality that is often assumed or overlooked. The aggressive and competitive nature of today's market demands more precise and powerful tools for defining flavor and flavor quality. Traditional as well as more recent methods for evaluating dairy flavor are reviewed. The application of defining sensory flavors to fundamental research on flavor chemistry, product understanding, and effective marketing is addressed.     

Distancing after group success and failure: Basking in reflected glory and cutting off reflected failure.

Two image-maintenance processes by which people manipulate their association with others were tested: the tendency to bask in reflected glory as a means of increasing one's association with successful others and the tendency to cut off reflected failure as a means of decreasing one's association with unsuccessful others. 102 undergraduates were initially involved in a group task and were then assigned to 1 of 3 group-performance feedback conditions: failure, no information, or success. Self-report and behavioral (taking and wearing of team badges) dependent measures of distancing showed that Ss in the failure group manifested less association with their group than did Ss in the no-information feedback and success groups; there was a tendency on behavioral but not self-report measures for Ss in the success group to manifest more association with their group than for Ss in the no-information feedback group. Therefore, more support was found for the cutting-off-reflected-failure process than for the basking-in-reflected-glory process as an image-maintenance tactic. Because Ss truly identified with their group's relative sense of failure or success, it is suggested that it was this identification process that appeared to have driven Ss' distancing behaviors in relation to their groups. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Impact of Iron on the Bleaching Efficacy of Hydrogen Peroxide in Liquid Whey Systems

Whey is a value‐added product that is utilized in many food and beverage applications for its nutritional and functional properties. Whey and whey products are generally utilized in dried ingredient applications. One of the primary sources of whey is from colored Cheddar cheese manufacture that contains the pigment annatto resulting in a characteristic yellow colored Cheddar cheese. The colorant is also present in the liquid cheese whey and must be bleached so that it can be used in ingredient applications without imparting a color. Hydrogen peroxide and benzoyl peroxide are 2 commercially approved chemical bleaching agents for liquid whey. Concerns regarding bleaching efficacy, off‐flavor development, and functionality changes have been previously reported for whey bleached with hydrogen peroxide and benzoyl peroxide. It is very important for the dairy industry to understand how bleaching can impact flavor and functionality of dried ingredients. Currently, the precise mechanisms of off‐flavor development and functionality changes are not entirely understood. Iron reactions in a bleached liquid whey system may play a key role. Reactions between iron and hydrogen peroxide have been widely studied since the reaction between these 2 relatively stable species can cause great destruction in biological and chemical systems. The actual mechanism of the reaction of iron with hydrogen peroxide has been a controversy in the chemistry and biological community. The precise mechanism for a given reaction can vary greatly based upon the concentration of reactants, temperature, pH, and addition of biological material. In this review, some hypotheses for the mechanisms of iron reactions that may occur in fluid whey that may impact bleaching efficacy, off‐flavor development, and changes in functionality are presented. Practical Application: Cheese whey is bleached to remove residual carotenoid cheese colorant. Concerns regarding bleaching efficacy, off‐flavor development, and functionality changes have been reported for whey proteins bleached with hydrogen peroxide and benzoyl peroxide. It is very important for the dairy industry to understand how whey bleaching can impact flavor and functionality of dried ingredients. Proposed mechanisms of off‐flavor development and functionality changes are discussed in this hypothesis paper.     

Effects of milk fat,casein, and serum protein concentrations on sensory properties of milk-based beverages

Our goal was to determine the effect of systematically controlled variation in milk fat, true protein, casein, and serum protein concentrations on the sensory color, flavor and texture properties, instrumental color and viscosity, and milk fat globule size distribution of milk-based beverages. Beverage formulations were based on a complete balanced 3-factor (fat, true protein, and casein as a percentage of true protein) design with 3 fat levels (0.2, 1.0, and 2.0%), 4 true protein (TP) levels (3.00, 3.67, 4.34, and 5.00%) within each fat level, and 5 casein as a percentage of true protein (CN%TP) levels (5, 25, 50, 75, and 80%) within each protein level (for a total of 60 formulations within each of 2 replicates). Instrumental measures of Hunter L and a values and Commission Internationale de l'Éclairage (CIE) b* values, instrumental viscosity, particle size, flavor, sensory texture and sensory appearance evaluations were done on each pasteurized/homogenized beverage formulation. Within each of the 3 fat levels, higher serum protein concentration drove higher aroma intensity, sweet aromatic, cooked/sulfur, cardboard/doughy flavors, and sensory yellowness scores, whereas higher casein concentration drove higher instrumental viscosity in milk protein beverages. Increasing serum protein concentration increased yellowness, sweet aromatic, aroma intensity, cooked/sulfur, and cardboard/doughy flavors across all fat levels and also had the largest effect on L, a, and b* values, sensory whiteness, and opacity within each fat level. Increases in true protein increased throat cling and astringency intensities. Increases in fat concentration were correlated with higher L, a, and b* values, larger particle size, and increased sensory whiteness, mouth coating, cooked/milky, and milkfat flavors. Multiple linear regression of L, a, and b* values produced better predictions of sensory whiteness and yellowness of pasteurized milk protein beverages than simple linear regression of L or b* values, respectively. Formulating milk protein beverages to a higher true protein level increased astringency regardless of fat level. When formulating milk protein beverages, a product developer has a wide range of milk-based protein ingredient choices that differ in price and change price relationship across time. Understanding the expected relative effect of different milk protein ingredients on the textural and flavor characteristics of milk-based beverages could be used to help guide product reformulation decisions and ingredient choices to achieve a specific sensory profile while controlling total beverage ingredient cost.     

Enhancement of the functional properties of whey protein by conjugation with maltodextrin under dry‐heating conditions

Conjugation of whey protein isolate (WPI) and maltodextrin (MD, dextrose equivalent of 6) was achieved by dry‐heating at an initial pH of 7.0, at 60 °C and 79% relative humidity, with WPI: MD6 ratio of 1:1, for up to 24 h. Conjugation was achieved with limited development of colour and advanced Maillard products on 24 h of heating. Conjugation increased the protein solubility at pH 4.5, by 7.1–8.5%, compared to the unheated and heated WPI controls. Conjugation of WPI with MD6 enhanced the stability and retention of clarity in protein solutions heated at 85 °C for 10 min with 50 mM added NaCl.