Xanthine Oxidase Activity and Development of Spontaneously Oxidized Flavor in Milk

Previous studies indicated there was a relationship between xanthine oxidase activity and development of oxidized flavor in milk. Additional studies were made of this observation. Enzyme activity was determined by a polarographic technique, flavor development was measured by means of spectrophotometry and gas and partition chromatography. Conclusions of the studies are 1) That high xanthine oxidase activity can be correlated with spontaneously oxidized flavor; 2) that lability of C~8 unsaturated fatty acids toward enzymatic oxidation was related to degree of unsaturation, i.e., linolenic acid was oxidized rapidly, linoleie acid at a very slow rate, and oleic acid unoxidized.