[Nutritional study of the membranes of S. cerevisiae. 1. Chemical composition and viscosity]

After an enzymic auto-degradation of their cytoplasma, the residue of the yeast (S. cerevisiae) contains a thick cell wall and a thin plasma membrane. These total membranes have the following composition in dry substance: proteins = 20,5%, lipids = 31,5%, carbohydrates = 42,0%, and ash = 3,7%. About 85% of carbohydrates (glycans) are easily hydrolysable by chemical method and should be digestible by the non-ruminant species. Proteins, contain 6,9% of lysine, 6,35% of threonine and have only one serious deficit, that of methionine which is 57%. These proteins seem to be resistant to the Maillard reaction. The percentage of in vitro digestible lysine increases when the membranes have undergone a heating of sufficient intensity. The methods of the treatment may give to the membranes an important apparent viscosity. These membranes could play the part of thickening and gelifiant agent in food technology. They also might constitute an interesting source of proteins because of its concentration in lysine and threonine.