Bioconversion of sugar industry by-products—molasses and sugar beet pulp for single cell protein production by yeasts

Abstract

In the bioconversion studies of molasses and sugarbeet pulp to single cell protein by four Candida spp. ( utilis, tropicalis, parapsilosis and solani) maximum protein content of 37.5 and 43.4% was achieved from the two substrates, respectively, in 48 h. Candida utilis and C. tropicalis performed better than the other yeasts. The maximum bioconversion efficiency for molasses (43%) was given by C. parapsilosis and for beet pulp (46%) by C. tropicalis in 48 h batch flask fermentations. The bioconversion of beet pulp under controlled conditions was studied using C. tropicalis in a 51 fermentor, which gave 29 and 48% product recovery with 39 and 25% protein level, in a two- and one-stage process, respectively. The one-stage process (simultaneous saccharification and fermentation) was also run in a larger volume and gave 50% product recovery with 29% protein content. The results are discussed in terms of biomass yield, protein content and bioconversion efficiency of yeasts under each condition.