Cccxiii. Irradiation of Fats

IN any attempt to study the oxidative effect of irradiation of fats, it is obvious that the methods of analysis employed must play an important part. The tests which may be applied to oxidized fats are characterized by lack of precision as regards both the actual quantitative expression and the knowledge of the chemistry involved. Reference to the paper by Lampitt et al. [1935] will show that three methods were selected to illustrate the application of the irradiation technique which was described. These methods had been studied with the object of exact standardization of procedure and an early communication on the subject was confidently predicted. Since the publication of the paper in 1935, however, further investigation has resulted in the application of the Zeiss photometer to the measurement of the Kreis test intensity, and in the development of a modification of the Issoglio determination, which yields figures very different from those usually obtained. The present paper details the results of this work, together with certain references to the aldehyde value [Lea, 1934] and the peroxide value [Lea, 1931]. Many workers have indicated the complexity of the changes which take place when comparatively simple chemical substances are irradiated and it can be assumed that the changes are even more complicated in the case of fats. Much has been written in an endeavour to explain and interpret the results of chemical examination of oxidized fats but such speculations cannot be regarded as being really profitable with the meagre data available. The authors have carried out certain work in an endeavour to correlate the results obtained on a series of fats using the tests mentioned. These results are recorded and certain tentative conclusions have been drawn regarding the interrelationship of the substances determined by the various methods.