FROM BIOETHANOL WASTE TO A PROTEIN-RICH FEEDSTOCK - A NEW TECHNOLOGY

Abstract

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 molasses-enriched vinasse were tested and finally a microbial growth enhancer (MGE) was incorporated to the media to ensure its optimisation. MGE-supplemented vinasse at 0.03 kg/m3 was found optimum for yeast propagation. At industrial scale μmax ≥ 0.33/h was obtained which allowed a stable behaviour of the culture at this scale and a significant industrial productivity. Yeast biomass from vinasse showed a composition and amino acid profile very similar to those previously obtained from molasses medium. A nutritional test demonstrated that vinasse Ìs yeast is an excellent source of proteins for animal feeding and an efficient pollution reducer.