Method for the valorisation of yeast biomass resulting from the production of ethanol

Abstract

The invention relates to compositions rich in yeast proteins, methods for producing processing wheat for recovery of the compositions rich in yeast proteins, and uses therefor as animal feed.

1 . A process for recovering a composition rich in yeast proteins from a distillation residue resulting from ethanol production, comprising:
 a) preparing a fermentable must comprising at least 40% by weight of wheat starch, less than 10% of vegetable proteins and between 3% and 6% of residual fibers;   b) enzymatically hydrolyzing the fermentable must to produce a hydrolyzate;   c) fermenting the hydrolysate;   d) distilling the fermented product of step c) to obtain a distillation residue;   e) separating the distillation residue so as to obtain: a first fraction (A) rich in yeast proteins and containing residual fibers; a second fraction (B) comprising soluble products of the distillation residue; and   f) drying of the fraction (A) so as to obtain a composition rich in yeast proteins.   
     
     
         2 . The process according to  claim 1 , wherein step a) comprises preparing a wheat starch milk comprising:
 removal of the wheat cereal fibers by milling and sieving; and   removal of the gluten by leaching.   
     
     
         3 . The process according to  claim 1 , wherein the fermentable must further comprises starch originating from sources other than wheat, and selected from chosen from corn, rye, barley, oat, triticale, spelt, millet, sorghum, horse bean, potato, sweet potato, rice, quinoa, chestnut, lentil, chickpea, bean, broad bean, cassava or buckwheat starch, or mixtures thereof. 
     
     
         4 . The process according to  claim 1 , wherein the fermentable must further comprises a supplement of fermentable materials comprising sugars or glucose syrups resulting from starch hydrolysis. 
     
     
         5 . The process according to  claim 1 , wherein the fermentable must includes substantially wheat starch milk. 
     
     
         6 . The process according to  claim 1 , said separating is carried out using a decanting device. 
     
     
         7 . The process for recovering a pulverulent composition rich in yeast proteins according to  claim 1 , comprising drying fraction (A) in a dispersion dryer. 
     
     
         8 . A composition rich in yeast proteins, comprising:
 a total protein content of between 25% and 35%;   a fiber content of between 40% and 50%;   a lipid content of between 8% and 12%;   a reducing sugar content of less than 2%; and   an ash content of less than 3%.   
     
     
         9 . The composition according to  claim 8 , further comprising between 4 and 8 g of lysine per 100 g of protein. 
     
     
         10 . The composition of  claim 8 , prepared according to the process according to the process of  claim 1 . 
     
     
         11 . An animal feed comprising the composition of  claim 8 . 
     
     
         12 . The process according to  claim 6 , wherein said decanting comprises using a horizontal decanter. 
     
     
         13 . The animal feed according to  claim 11 , further comprising between 4 and 8 g of lysine per 100 g of protein. 
     
     
         14 . The process according to  claim 1 , wherein said fermenting is conducted batchwise or continuously. 
     
     
         15 . The process of  claim 1 , wherein the fermenting is conducted in the presence of a yeast selected from one of  Saccharomyces, Schizosaccharomyces, Brettanomyces, Schwanniomyces, Candida  and  Pichia.    
     
     
         16 . The process of  claim 1 , wherein the fermenting is conducted at a temperature of between 25 and 35° C.