Spectroscopic changes in fatty acids

THE presence in butter fat of acids showing spectroscopic absorption in the ultra-violet region was established by Gillam et al. [1931]. Booth et al. [1935] showed that the absorptive acids were present in greater concentration in summer than in winter butter fat, and that the absorption could not be due to oleic acid, or to polyethylenic acids in their usual form as present in seed fats. Dann et al. [1935] found that when fats containing polyethylenic acids are given to the cows they are converted from the spectroscopically " pro-absorptive"' into the " absorptive " state. This phenomenon was similar to that found to occur in vitro on the prolonged refluxing of cod liver oil with alcoholic KOH [Dann & Moore, 1933]. The purpose of these notes is to record data obtained upon three specimens of butter obtained from cows under different nutritional treatments.