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% H2SO4 at 100 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 L1) was achieved at
35 C by S. cerevisiae y-1646 after 36 h when ZnCl2 (0.4 g L1) was added. Addition of NH4NO3
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.