Streamlined analysis of short-, medium-, and long-chain free fatty acids in dairy products

In dairy products free fatty acids (FFAs) with fewer than ten carbon atoms can impart both desirable and undesirable (rancid) flavor notes, while long-chain FFAs are responsible for a soapy taste. The determination of FFAs in milk, cheese and other dairy products is particularly complicated owing to two main factors, i.e. FFAs (2 to 20 carbon atoms) represent <0.5% of total fat and many of the short-chain FFAs are extremely volatile. The best approach is to analyze short-chain FFAs (<C10) separately from the long-chain FFAs. Short-chain FFA can be extracted in soap form with water and then upon acidification of the extract short chain FFAs can be extracted into ether for GC analysis. Long chain FFA can be extracted with a mixture of ethenheptane (1:1, v/v), resulting in an extract that contains the whole range of lipids including FFAs. The present paper will describe a streamlined approach (utilizing an aminopropyl bonded phase column) for the analysis of total FFAs in dairy products.