Simple Determination of Ethanol, Propionic Acid and Sorbic Acid in Bread, Cake and Cheese

Abstract

A simple gas chromatographic method was developed for the determination of ethanol, propionic acid and sorbic acid in bakery products and cheese.
A sample was subjected to steam distillation. The distillate was injected directly into a gas chromatographic column packed with porous polymer beads, and equipped with a flame ionization detector, for determining ethanol and propionic acid. For the determination of sorbic acid, the distillate was acidified by adding formic acid solution, and the resulting solution was injected into a short gas chromatographic column packed with porous polymer beads.
Recovery of each compound added to food samples at a level of 0.50 or 1.00g/kg was more than 90%, the coefficients of variation being less than 7% for ethanol and 4% for propionic acid and sorbic acid. The detection limit for each compound in food samples was 0.02g/kg. The analytical results for 60 samples of bakery products and 14 samples of cheese are also presented.