Destructive Distillation of Casein in a Partial Vacuum.

Abstract

According to recent views, proteins are made up of heterocyclic complexes known to yield cyclic anhydrides when partially hydro-lyzed, and amino acids when completely hydrolyzed. Since the character of the decomposition products seems to depend upon the nature of the degradation process, the desirability of investigating the products formed by methods other than hydrolytic is apparent. The intention in the present work was to adapt the methods of Johnson and Daschavsky, to casein and, as far as possible, to obtain quantitative information in regard to the products of decomposition. Casein was selected as the basic material because it may readily be obtained in quantity. It was also desired to make a comparison between this relatively complete protein and silk fibroin. The distillation was conducted in an iron pipe 24 inches long and 3 ½ inches in diameter. The pipe was fitted at each end with an iron screw cap. An iron delivery tube, 20 inches long and ¾ inch in diameter, was threaded into the center of one of the caps. The screw caps were rendered gas tight by coating the threads with white lead. Graphite proved to be unsatisfactory for this purpose. Five hundred gram portions of white, finely powdered, commercial casein were heated in the iron pipe on an ordinary combustion furnace for each of the six runs. By slightly tilting the furnace, the molten material was prevented from clogging the delivery pipe. For collecting the liquid and gaseous products, 10 round bottom, side neck, Pyrex flasks were connected in series to the delivery tube. A manometer and a good water pump were attached to the terminal flask. An oil pump was used in some of the experiments but it was found to be unsatisfactory due to its failure to maintain a constant vacuum.