A Simplified Extraction-Distillation Method for the Determination of the Volatile Fatty Acids of Cheese

Abstract

A method for determining the volatile fatty acids in cheese was developed based upon 2 distillations, one associated with the ether extract and the other with the residual material. An acid-cheese mixture was ether extracted and the fatty acids removed with dilute alkali. The ether was driven off the alkali rinses, acidified, refluxed to remove CO2, and distilled in a Kjeldahl apparatus in the presence of MgSO4 until crystallization occurred. In the meantime, 250 ml. water were added to the residual material containing MgSO4 and distilled until 280 ml. of distillate were collected. The sum of the 2 titrations from the distillates plus the alcohol rinse of insoluble fatty acids represented total volatile acids. This new method is short, accurate and required no special apparatus. In the presence of MgSO4, acids from acetic through lauric were quantitatively recovered, but myristic acid was incompletely recovered. Non-volatile fatty acids exerted some retentive effect on the distillation of volatile fatty acids with the degree of retention being in direct relationship to the number of carbon atoms present in the volatile acids. There was no retentive effect on butyric and caproic acids.