E.A. Foegeding

Properties of whey and egg white protein foams

Abstract Foams made of varying concentrations (2–20% w/v protein) of egg white and whey protein isolate were compared by measuring rheological and microstructural properties. Egg white proteins formed foams with higher yield stress (τ) at lower protein concentrations and less whipping time than whey protein isolate foams. The model of Princen and Kiss [J. Coll. Interf. Sci. 128 (1989) 176] predicts a relationship among τ, surface tension (σ), phase volume (φ), and bubble size (R32). This was supported by τ increasing with φ, and the relationship between τ and φ1/3 becoming more linear as protein concentration increased. However, egg white foams had yield stress values as much as 100 Pa greater than whey protein foams, despite having similar phase volumes, bubble size, and lower surface tensions. The experimentally determined factors, Y(φ), for egg white and whey protein isolate foams were within the range determined by Princen and Kiss [J. Coll. Interf. Sci. 128 (1989) 176] for concentrated emulsions. Egg white foams were different in that the values for Y(φ) increased at lower phase volumes than for whey protein isolate foams or concentrated emulsions. These results suggest that specific proteins contribute to foam τ by some means in addition to altering surface properties.

Food Oral Processing: Conversion of Food Structure to Textural Perception

Food oral processing includes all muscle activities, jaw movements, and tongue movements that contribute to preparing food for swallowing. Simultaneously, during the transformation of food structure to a bolus, a cognitive representation of food texture is formed. These physiological signals detected during oral processing are highly complex and dynamic in nature because food structure changes continuously due to mechanical and biochemical breakdown coupled with the lubricating action of saliva. Multiple and different sensations are perceived at different stages of the process. Although much work has focused on factors that determine mechanical (e.g., rheological and fracture) and sensory properties of foods, far less attention has been paid to linking food transformations that occur during oral processing with sensory perception of texture. Understanding how food structure influences specific patterns of oral processing and how these patterns relate to specific textural properties and their cognitive representations facilitates the design of foods that are nutritious, healthy, and enjoyable.

Use of Whey Protein Soluble Aggregates for Thermal Stability—A Hypothesis Paper

Forming whey proteins into soluble aggregates is a modification shown to improve or expand the applications in foaming, emulsification, gelation, film-formation, and encapsulation. Whey protein soluble aggregates are defined as aggregates that are intermediates between monomer proteins and an insoluble gel network or precipitate. The conditions under which whey proteins denature and aggregate have been extensively studied and can be used as guiding principles of producing soluble aggregates. These conditions are reviewed for pH, ion type and concentration, cosolutes, and protein concentration, along with heating temperature and duration. Combinations of these conditions can be used to design soluble aggregates with desired physicochemical properties including surface charge, surface hydrophobicity, size, and shape. These properties in turn can be used to obtain target macroscopic properties, such as viscosity, clarity, and stability, of the final product. A proposed approach to designing soluble aggregates with improved thermal stability for beverage applications is presented.

Effect of bleaching whey on sensory and functional properties of 80% whey protein concentrate

Whey is a highly functional food that has found widespread use in a variety of food and beverage applications. A large amount of the whey proteins produced in the United States is derived from annatto-colored Cheddar cheese. Color from annatto is undesirable in whey and must be bleached. The objective of this study was to compare 2 commercially approved bleaching agents, benzoyl peroxide (BP) and hydrogen peroxide (HP), and their effects on the flavor and functionality of 80% whey protein concentrate (WPC80). Colored and uncolored liquid wheys were bleached with BP or HP, and then ultrafiltered, diafiltered, and spray-dried; WPC80 from unbleached colored and uncolored Cheddar whey were manufactured as controls. All treatments were manufactured in triplicate. The WPC80 were then assessed by sensory, instrumental, functionality, color, and proximate analysis techniques. The HP-bleached WPC80 were higher in lipid oxidation compounds (specifically hexanal, heptanal, octanal, nonanal, decanal, dimethyl disulfide, and 1-octen-3-one) and had higher fatty and cardboard flavors compared with the other unbleached and BP-bleached WPC80. The WPC80 bleached with BP had lower norbixin concentrations compared with WPC80 bleached with HP. The WPC powders differed in Hunter color values (L, a, b), with bleached powders being more white, less red, and less yellow than unbleached powders. Bleaching with BP under the conditions used in this study resulted in larger reductions in yellowness of the powders made from whey with annatto color than did bleaching with HP. Functionality testing demonstrated that whey bleached with HP treatments had more soluble protein after 10 min of heating at 90°C at pH 4.6 and pH 7 than the no-bleach and BP treatments, regardless of additional color. Overall, HP bleaching caused more lipid oxidation products and subsequent off-flavors compared with BP bleaching. However, heat stability of WPC80 was enhanced by HP bleaching compared with control or BP-bleached WPC80.

Comparison of functional properties of 34% and 80% whey protein and milk serum protein concentrates

This study compared the functional properties of serum protein concentrate (SPC) with whey protein concentrate (WPC) made from the same milk and with commercial WPC. The experimental SPC and WPC were produced at 34% or 80% protein from the same lot of milk. Protein contents of WPC and SPC were comparable; however, fat content was much lower in SPC compared with WPC and commercial WPC. The effect of drying methods (freeze vs. spray drying) was studied for 34% WPC and SPC. Few differences due to drying method were found in turbidity and gelation; however, drying method made a large difference in foam formation for WPC but not SPC. Between pH 3 and 7, SPC was found to have lower turbidity than WPC; however, protein solubility was similar between SPC and WPC. Foaming and gelation properties of SPC were better than those of WPC. Differences in functional properties may be explained by differences in composition and extent of denaturation or aggregation.

Milk Protein Products | Whey Protein Products

Whey proteins, a coproduct of cheesemaking and casein manufacture, represent a rich and heterogeneous mixture of proteins with a broad range of nutritional and functional properties. Significant progress in the utilization of whey has been made in the past 30 years, especially with the current research findings on the health benefits of whey proteins and their derivatives. The future growth of whey utilization is expected to be led by the industry’s increasing focus on nutritional products, particularly in the dietary, sports, and clinical segments of the market. Functional properties of whey proteins in foods include solubility, dispersibility, heat stability, network formation (gels and edible films), and surface activity (emulsions and foams). This article discusses the production, processing, and applications of whey proteins and their derivatives.

The effect of microfiltration on color, flavor, and functionality of 80% whey protein concentrate

The residual annatto colorant in fluid Cheddar cheese whey is bleached to provide a neutral-colored final product. Currently, hydrogen peroxide (HP) and benzoyl peroxide are used for bleaching liquid whey. However, previous studies have shown that chemical bleaching causes off-flavor formation, mainly due to lipid oxidation and protein degradation. The objective of this study was to evaluate the efficacy of microfiltration (MF) on norbixin removal and to compare flavor and functionality of 80% whey protein concentrate (WPC80) from MF whey to WPC80 from whey bleached with HP or lactoperoxidase (LP). Cheddar cheese whey was manufactured from colored, pasteurized milk. The fluid whey was pasteurized and fat separated. Liquid whey was subjected to 4 different treatments: control (no bleaching; 50°C, 1 h), HP (250 mg of HP/kg; 50°C, 1 h), and LP (20 mg of HP/kg; 50°C, 1 h), or MF (microfiltration; 50°C, 1 h). The treated whey was then ultrafiltered, diafiltered, and spray-dried to 80% concentrate. The entire experiment was replicated 3 times. Proximate analyses, color, functionality, descriptive sensory and instrumental volatile analysis were conducted on WPC80. The MF and HP- and LP-bleached WPC80 displayed a 39.5, 40.9, and 92.8% norbixin decrease, respectively. The HP and LP WPC80 had higher cardboard flavors and distinct cabbage flavor compared with the unbleached and MF WPC80. Volatile compound results were consistent with sensory results. The HP and LP WPC80 were higher in lipid oxidation compounds (especially heptanal, hexanal, pentanal, 1-hexen-3-one, 2-pentylfuran, and octanal) compared with unbleached and MF WPC80. All WPC80 had >85% solubility across the pH range of 3 to 7. The microstructure of MF gels determined by confocal laser scanning showed an increased protein particle size in the gel network. MF WPC80 also had larger storage modulus values, indicating higher gel firmness. Based on bleaching efficacy comparable to chemical bleaching with HP, flavor, and functionality results, MF is a viable alternative to chemical or enzymatic bleaching of fluid whey.

Investigating the filled gel model in Cheddar cheese through use of Sephadex beads

Cheese can be modeled as a filled gel whereby milkfat globules are dispersed in a casein gel network. We determined the filler effects using Sephadex beads (GE Healthcare Life Sciences, Pittsburgh, PA) as a model filler particle. Ideally, such a model could be used to test novel filler particles to replace milkfat in low-fat cheese. Low-filler (6% particles), reduced-filler (16%), and full-filler (33%) cheeses were produced using either Sephadex beads of varying sizes (20 to 150 μm diameter) or milkfat. Small- and large-strain rheological tests were run on each treatment at 8, 12, and 18 wk after cheese manufacturing. Differences in rheological properties were caused primarily by the main effects of filler volume and type (milkfat vs. Sephadex), whereas filler size had no obvious effect. All treatments showed a decrease in deformability and an increase in firmness as filler volume increased above 25%, although the beads exhibited a greater reinforcing effect and greater energy recovery than milkfat.

A comparison of the gelling and foaming properties of whey and egg proteins

Publisher Summary Whey and egg white protein ingredients are often used in similar functional applications, which involve gelation or foam formation. This chapter compares the large-strain (fracture) rheological properties of heat-induced (80°C for 30 min) whey protein isolate (WPI) and egg white (EW) gels made under solution conditions, which are optimized for gel strength (fracture stress). Gels formed under these conditions had similar values for fracture stress over the range of 6–18% w/v protein. Gel deformability (fracture strain), had protein-specific trends. Fracture strain for WPI gels decreases as protein concentration increases, whereas fracture strain for EW gels remains constant. The stress–strain relationships for EW and WPI gels are characterized by calculating a ratio between the rigidity (stress/strain) at fracture and the rigidity at 30% of the fracture strain, called the rigidity ratio. Both EW and WPI gels have higher rigidity ratios (1.4–1.8) at low protein concentrations then shift to lower values, of around 1, as protein concentration increases. The various gels formed at different protein concentrations and heating times and temperatures could be fit to a master curve of rigidity ratio vs. fracture rigidity. The yield stress of EW and WPI foams is determined by a vane method. Egg white foams exhibit relatively high yield stresses, even at low protein concentration and short whipping time. Maximum yield stress occur at 8–10 min in egg white foams, while whey protein isolate foams require >15 min. The rheological properties of egg white and whey protein isolate foams and gels show protein-specific and protein-independent properties.

Flavor and Functional Characteristics of Whey Protein Isolates from Different Whey Sources.

This study evaluated flavor and functional characteristics of whey protein isolates (WPIs) from Cheddar, Mozzarella, Cottage cheese, and rennet casein whey. WPIs were manufactured in triplicate. Powders were rehydrated and evaluated in duplicate by descriptive sensory analysis. Volatile compounds were extracted by solid-phase microextraction followed by gas chromatography-mass spectrometry. Functional properties were evaluated by measurement of foam stability, heat stability, and protein solubility. WPI from Cheddar and Cottage cheese whey had the highest cardboard flavor, whereas sweet aromatic flavor was highest in Mozzarella WPI, and rennet casein WPI had the lowest overall flavor and aroma. Distinct sour taste and brothy/potato flavor were also noted in WPI from Cottage cheese whey. Consistent with sensory results, aldehyde concentrations were also highest in Cheddar and Cottage cheese WPI. Overrun, yield stress, and foam stability were not different (P > 0.05) among Cheddar, Mozzarella, and rennet casein WPI, but WPI foams from Cottage cheese whey had a lower overrun and air-phase fraction (P < 0.05). Cottage cheese WPI was more heat stable at pH 7 (P < 0.05) than other WPI in 4% protein solutions, and was the only WPI to not gel at 10% protein. Cottage cheese WPI was less soluble at pH 4.6 compared to other WPI (P < 0.05) and also exhibited higher turbidity loss at pH 3 to 7 compared to other WPI (P < 0.05). This study suggests that WPI produced from nontraditional whey sources could be used in new applications due to distinct functional and flavor characteristics.