Production of bioethanol and associated by-products from potato starch residue stream by Saccharomyces cerevisiae

Potato starch residue stream produced during chips manufacturing was used as an economical source for biomass and bioethanol production by Saccharomyces cerevisiae. Results demonstrated that 1% H(2)SO(4) at 100 degrees C for 1 h was enough to hydrolyze all starch contained in the residue stream. Two strains of S. cerevisiae (y-1646 and commercial one) were able to utilize and ferment the acid-treated residue stream under both aerobic and semi-anaerobic conditions. The maximum yield of ethanol (5.52 g L(-1)) was achieved at 35 degrees C by S. cerevisiae y-1646 after 36 h when ZnCl(2) (0.4 g L(-1)) was added. Addition of NH(4)NO(3) as a source of nitrogen did not significantly affect either growth or ethanol production by S. cerevisiae y-1646. Some secondary by-products including alcohol derivatives and medical active compound were found to be associated with the ethanol production process. (C) 2010 Elsevier Ltd. All rights reserved.