Patent GB-450529-A (GB)
Title: Improvements relating to yeast or protein preparations
IPC: C12N9/60
Filed: 1934-10-20
Abstract: The protein of yeast is degraded by plasmolysis and autolysis with the aid of a cell poison, such as an alkyl ester, e.g. ethyl acetate, innocuous to or not destructive of the liberated proteolytic enzymes, a pH value of 6,3 to 6,6 and temperatures below 50 DEG C., being maintained during the autolysis.  The temperature is preferably maintained at 35 to 36 DEG  C. and the pH value regulated by a buffer such as trisodium phosphate.  Other proteins, preferably vegetable, e.g. soya meal, distillers' grains, brewers' grains, and cereals, even after bran and germ extraction, may be degraded concurrently with or by the degradation products of the yeast, to yield products rich in enzymes and vitamins and suitable for human consumption. Auxiliary enzymes, e.g. papain or amylase may be introduced to accelerate the process.  In an example, yeast was plasmolysed by 5 per cent ethyl acetate and autolysed using sodium phosphate to buffer the solution to a pH of 6,34.  In another example, bakers' yeast was plasmolysed by 10 per cent ethyl acetate and autolysed using 10 per cent toluene as an antiseptic.  In an example, using the autolysed yeast to hydrolyse other proteins, soya meal extracted with acetone was hydrolysed with a yeast autolysed as above.  From the filtered product, tyrosine was crystallized out before evaporation to dryness to obtain a powder of agreeable taste.  The cell-poison effecting plasmolysis is preferably one having substantial lipoid and water-solubilities and innocuous to the proteolytic enzymes of the yeast.  Ethyl acetate is preferred, toluene being slow in action and chloroform and carbon tetrachloride destroying the enzyme.ALSO:The protein of yeast is degraded by plasmolysis and antolysis with the aid of a cell poison, such as an alkyl ester, e.g. ethyl acetate, innocuous to or not destructive of the liberated proteolytic enzymes, a pH value of 6,3 to 6,6 and temperatures below 50 DEG  C., being maintained during the antolysis.  The temperature is preferably maintained at 35 to 36 DEG  C., and the pH value regulated by a buffer such as trisodium phosphate.  Other proteins, preferably vegetable, e.g. soya meal, distiller's grains, brewer's grains, and cereals even after bran and germ extraction, may be degraded concurrently with or by the degradation products of the yeast, to yield products rich in enzymes and vitamins and suitable for human consumption. Auxiliary enzymes, e.g. papain or amylase may be introduced to accelerate the process.  In an example yeast was plasmolyzed by 5 per cent ethyl acetate and autolyzed using sodium phosphate to buffer the solution to a pH of 6,34.  In another example bakers' yeast was plasmolyzed by 10 per cent ethyl acetate and autolyzed using 10 per cent toluene as an antiseptic.  In an example using the autolyzed yeast to hydrolyze other proteins, soya meal extracted with acetone was hydrolyzed with a yeast autolyzed as above.  From the filtered product, tyrosine was crystallized out before evaporation to dryness to obtain a powder of agreeable taste. The cell poison effecting plasmolysis is preferably one having substantial lipoid and water-solubilities and innocuous to the proteolytic enzymes of the yeast.  Ethyl acetate is preferred, toluene being slow in action and chloroform and carbon tetrachloride destroying the enzyme.