Improved Technique for Analysis of Free Fatty Acids in Butteroil and Provolone Cheese

Abstract

A method is described for isolating the free fatty acids (FFA) of butteroil and Provolone cheese, using the silicic acid-KOH column of McCarthy and Duthie. The FFA were eluted from the column with phosphoric acid in diethyl ether. After addition of methanol, the FFA and excess phosphoric acid were titrated with methanolic KOH. The potassium phosphate salts were sedimented and the supernatant evaporated to dryness under nitrogen. Experiments indicated no saponification of triglycerides and no esterification of FFA during the above manipulations. Butyl esters were prepared using sulfuric acid as a catalyst, and esters from butyrate through linolenate were estimated with gas-liquid chromatography, using heptanoic and heptadecanoic acids as internal standards. FFA were determined in three different samples of butteroil and in Provolone cheese. In butteroil the short-chain FFA were low and the long-chain FFA were high in concentration. In Provolone cheese the short-chain FFA were extremely high. Butyric acid was highest in concentration of all the FFA. © 1967, American Dairy Science Association. All rights reserved.