The nutritional value of tuberin, the globulin of potato

Abstract

Tuberin was prepared from potato juice by heat coagulation. One hundred and ninety-two kgm. of potatoes yielded 553gm. of the tuberin, which contained 14.8% N, 1.1% S and 1.8% ash. A yield of 0.3 gm. of a substance giving all the color reactions of solanin and having a very bitter taste was obtained from the filtrate from the 553 gms. of tuberin. The tuberin was compared with caseinogen as a source of protein for rats. The biological values of the two proteins were determined (Mitchell''s method) and their value for growth in accordance with the method of Osborn, Mendel and Ferry. The biological value of tuberin was found to be 71 at an intake level of 8%, that of caseinogen, 68. At a level of 7.8%, tuberin gave a maximal gain of 2 gms. body weight per gm. of protein ingested. The conclusion is reached that "tuberin is a good and complete protein.".