A Bioethanol Waste Challenge being a Source of High-Quality ProteinRich Feedstock: A New Technology

Microbial biomass protein from Candida utilis yeast was produced using distillery vinasse as the sole source of carbon and energy. The process was carried out from lab scale to 200 m3 fermentors. Propagation media have to be supplemented with nutrients since vinasse cannot provide all compounds needed for a stable operation. Different mixtures of molassesenriched vinasse were tested and finally, a Microbial Growth Enhancer (MGE) was incorporated into the media to ensure its optimization. MGE-supplemented vinasse at 0.03 kgm3 was found optimum for yeast propagation. At an industrial scale, µmax ≥ 0.33 h-1 was obtained which allowed a stable behavior of the culture at this scale and significant industrial productivity. Yeast biomass from vinasse showed a composition and amino acid profile very similar to those previously obtained from molasses medium. Nutritional tetestsemonstrated that vinasse´s yeast is an excellent source of proteins for animal feeding and an efficient pollution reducer.