Abstract: The primary off flavors in dried whey proteins have been attributed to lipid oxidation products. A deeper understanding of lipid oxidation in fluid whey is crucial to understand how to minimize off flavors in dried whey protein. The objectives of this study were to further elucidate the role of storage and starter cultures as sources of lipid oxidation in whey. Fluid Cheddar, Mozzarella, and rennet-set wheys were manufactured from skim and whole milk. Liquid wheys and milks were evaluated by descriptive sensory and volatile instrumental analysis within 2 h of manufacture and following storage for 3 d at 4 °C. Culture type greatly influenced the oxidative stability of liquid whey, with Cheddar and Mozzarella whey differing not only in sensory profile, but also in volatile compounds. The type of starter culture (Mozzarella compared with Cheddar) had more influence on flavor than the set type (acid compared with culture). Milks had lower relative abundances of volatile free fatty acids than their liquid whey counterparts. Volatile lipid oxidation products in wheys were higher than in their respective milks, but oxidation in both milks and wheys increased with storage time. Wheys from Cheddar starters displayed more oxidation products than wheys from Mozzarella starters. Starter media did not have an effect on the flavor or oxidative stability of liquid whey, however, culture strain influenced lipid oxidation of fluid whey.
Practical Application: Lipid oxidation products are primary contributors to whey ingredient off-flavors. Flavor plays a critical and limiting role in widespread use of dried whey ingredients, and enhanced understanding of flavor and flavor formation in fluid whey are industrially relevant. Results from this study demonstrate that oxidation occurs in milk prior to cheesemaking but that starter type and starter strain influence also oxidative stability and lipid oxidation off flavors in fluid whey.