Milk Lipase System. II. Comparison of Solvent Extraction and Churning Methods for Obtaining Fat from Milk for Free Fatty Acid Measurement

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Abstract
An extraction method involving the use of ethanol, ethyl ether and Skellysolve F was developed for the removal of fat from milk products for free fatty acid titration. The application of this method to rancid milk yielded fat averaging 30% higher in acidity than fat obtained by the conventional churning method with higher fat recoveries. The accuracy of the solvent method was essentially unaffected by the presence of lactic acid and/or formalin, and was particularly adaptable to the removal of fat from homogenized products of low fat content. Studies on the recovery of pure fatty acids from cream revealed the solvent method to be superior to the churning procedure for the lower fatty acids. Improved recovery of butyric acid added to cream resulted when low temps. and pressures were used for solvent removal. Chemical analyses of the fat obtained by churning and by extraction yielded similar results with the exception of the acid degree. Analysis of ethanolic soluble and insoluble fractions of solvent extracted fat failed to indicate definitely selective hydrolysis by milk lipase.