Abstract
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.