The oxidative stability of liquid Cheddar cheese whey was evaluated using 2 Lactococcus lactis starter cultures in combination and alone along with a control, utilizing glucono-delta-lactone for acid development. Fresh and stored whey were evaluated for volatile composition, free fatty acids, and flavor by descriptive sensory analysis. A significant increase in volatile lipid oxidation products, most notably, hexanal, occurred during storage, and a corresponding decline in the free fatty acid linoleic acid was found. The flavor and aroma characteristic, cardboardy, was correlated to the increase in volatile lipid oxidation products and the decline in linoleic acid. Evidence strongly suggested that lipid oxidation was initiated during whey production and escalated during storage and that the starter cultures significantly influenced the level of volatile lipid oxidation products. Further understanding of the impact of starter cultures on whey may allow for the production of higher quality whey ingredients with wider food application.

Homogenized milk packaged in polyethylene containers exposed to fluorescent lights showed flavor and vitamin deterioration. Off-flavor development began within 2 to 4 h after exposure to a lighting system simulating commercial display cases. Detection of light-induced flavor was slight, medium, and strong after 4, 7 and 24 h of exposure. Decreases in riboflavin and ascorbic acid were directly proportional to the amount of light exposure. Various types of colored lamps and lamp filters were tested to prevent this off-flavor and vitamin degradation in milk. Yellow lamps or yellow and green filters protected milk from off-flavor development for 30 to 40 h. It is evident that light-induced off-flavors and vitamin destruction in fluid milk packaged in polyethylene containers can be reduced by colored lamps and lamp filters.

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Commercial enzymes (protease and lipase) were used to produce highly flavored cheese-like hydrolysates from fluid milk. Free fatty acids, free amino acids, degree of proteolysis, and volatile profiles were assessed to suggest the importance of proteolytic and lipolytic activity on cheese flavor development. Free fatty acid liberation was maximized with the combined Flavourzyme TM (protease) and Palatase ® (lipase) treatment incubated at 30 ЊC, most likely due to synergism conferred by the protease. The Flavourzyme/Palatase samples incubated at 45 ЊC generated the highest total concentration of volatile compounds. The addition of Flavourzyme generated free amino acids and low molecular weight peptides (< 1400 MW).

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