Analysis of free fatty acids in whey products by solid-phase microextraction

To evaluate the impact of Cheddar cheese starter cultures on the level of f ree fatty acids in liquid whey, a solid-phase microextraction (SPME) techni que was utilized. The determination of response factors relative to an inte rnal standard and the verification of linearity over a wide concentration r ange allowed for the quantitation of free fatty acids in experimentally pro duced liquid whey and in a wide range of dry whey ingredients. Results indi cated that whey produced with a Lactococcus lactis subsp. lactis starter cu lture contained the highest level of total free fatty acids with significan tly higher levels of lauric, myristic, and palmitic acids. Significant decl ines in oleic, linoleic, and palmitic acid occurred during storage. Commerc ial whey ingredients demonstrated a linear increase in free fatty acids wit h increasing percent protein, except for whey protein isolate, which had th e lowest concentration. The use of SPME for the rapid analysis of free fatt y acids in whey products should allow for further research to determine the importance of these compounds on the quality and stability of whey product s.