Some Observations on the Flavor of Acid Whey

Effects of replacing buttermilk with yogurt acid whey in ranch dressing

Greek-style yogurt has expanded from 5 to 50% of the US yogurt market in the past decade, accompanied by a corresponding increase in production of its by-product: yogurt acid whey (YAW). Yogurt acid whey qualities (e.g., low pH, mineral content, astringency, and saltiness) present challenges for processing, disposal, and ingredient use. A shelf-stable ranch dressing was formulated by replacing buttermilk in the control with YAW and concentrated YAW (6.3 to 25.2 °Brix). Added salt, gums, and acids were adjusted. The effects of buttermilk substitution on stability were studied on pasteurized samples (8 mo at room temperature). A consumer sensory study (n = 96) was conducted utilizing hedonic and just-about-right scales. Purchase intent and demographic data were also collected. A focus group (n = 7) evaluated the sensorial attributes of the samples after 6 mo. The experiment was performed in triplicate and all instrumental analyses (pH, soluble solids as °Brix, water activity, refraction index, and color) were conducted in triplicate for statistical analysis. Increasing the gum content in YAW samples resulted in equivalent texture liking compared with the control. Matching the control's NaCl concentration resulted in undesirable higher saltiness. The pH of the 18.9 °Brix YAW ranch sample without lactic acid added was under 4.6, with no effect on flavor liking. Increasing concentrations of YAW decreased L* and water activity, and increased the refractive index and hue. The YAW samples presented minimum changes over 8 mo of storage and had better water retention than the control. We conclude that 15 to 17 °Brix YAW is the optimal replacement for buttermilk in a dressing. The formulation of dressings may be accomplished successfully, sustainably, and cost effectively, with minor processing adjustment, by substituting buttermilk with YAW.

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.

Sensory Characteristics and Related Volatile Flavor Compound Profiles of Different Types of Whey

To characterize the flavor of liquid whey, 11 samples of whey representing a wide range of types were sourced from cheese and casein-making procedures, either industrial or from pilot-plant facilities. Whey samples were assessed for flavor by descriptive sensory evaluation and analyzed for headspace volatile composition by proton transfer reaction-mass spectrometry (PTR-MS). The sensory data clearly distinguished between the samples in relation to the processes of manufacture; that is, significant differences were apparent between cheese, rennet, and acid wheys. For Mozzarella and Quarg wheys, in which fermentation progressed to low pH values, the starter cultures used for cheese making had a significant influence on flavor. In comparison, Cheddar and Gouda wheys were described by milk-like flavors, and rennet casein wheys were described by "sweet" (oat-like and "sweet") and thermally induced flavors. The volatile compound data obtained by PTR-MS differentiated the samples as distinctive and reproducible "chemical fingerprints". On applying partial least squares regression to determine relationships between sensory and volatile composition data, sensory characteristics such as "rancid" and cheese-like odors and "caramelized milk," yogurt-like, "sweet," and oat-like flavors were found to be related to the presence and absence of specific volatile compounds.

Whey protein concentrates and isolates: processing and functional properties

Substantial progress has been made in understanding the basic chemical and structural properties of the principal whey proteins, that is, beta-lactoglobulin (beta-Lg), alpha-lactalbumin (alpha-La), bovine serum albumin (BSA), and immunoglobulin (Ig). This knowledge has been acquired in terms of: (1) procedures for isolation, purification, and characterization of the individual whey proteins in buffer solutions; and (2) whey fractionation technologies for manufacturing whey protein concentrates (WPC) with improved chemical and functional properties in food systems. This article is a critical review of selected publications related to (1) whey fractionation technology for manufacturing WPC and WPI; (2) fundamental properties of whey proteins; and (3) factors that affect protein functionality, that is, composition, protein structure, and processing.