Deproteination of yeast cells

The process of making a deproteinized yeast cell membrane product which comprises

• filling to capacity a vessel solely with compressed yeast having a moisture content of about 70%,
• sealing the filled vessel so that the vessel is air-tight and the yeast therein is cut off from communication with atmospheric air,
• heating the yeast in the vessel to about 55.degree.C and maintaining the yeast at about 55.degree.C under anaerobic conditions until liquifaction and autolysis of the yeast has commenced as indicated by the yeast beginning to darken and turn brown,
• thereafter lowering the internal pressure of said sealed vessel to less than atmospheric pressure and introducing an inert gas into said vessel to create a current of inert gas through the vessel and maintain said anaerobic conditions,
• evaporating residual water from yeast in said vessel while continuously agitating said yeast in the presence of said current of inert gas under said lower pressure at about 55.degree.C until the proportion of residual water in said yeast has been reduced to about 40% to 50%,
• maintaining the yeast under said reduced pressure, said current of inert gas, said anaerobic conditions and said temperature until autolysis is complete and substantially more than 50% of the naturally present protein gel of the yeast cells has been expelled from within the yeast cells to form a pasty yeast product mixture of a water soluble material and deproteinated yeast cell membranes,
• recovering the cell membranes from said mixture by centrifugation, and washing the cell membranes with water.