High Cell Density Yeast Production: Process Synthesis and Scale-Up

Abstract

A high cell density process for C. utilis production on molasses was developed. A demonstration plant producing 70.8 kg h−1 was operated in 1990 and 1991. C. utilis was continuously cultivated at cell densities of 80 to 110 kg m−3 in an especial 10.5 m3 jet loop fermentor having an oxygen transfer rate of 350 mol O2m−3 h−1 at 1.1 VVM. The yeast was concentrated by a rotary filter yielding a 24% solids yeast cake, which is continuously thermolysed. The thermolysed product-which can be used as a natural flavor enhancer for food and fed — had a protein digestibility higher than 90%. The technology requires 20% less in capital investment and consumes only one third of the water involved in fermentation, if compared with conventional yeast production processes, being therefore a highly competitive alternative.