Effect of photocatalytic pretreatment of potato starch for bioethanol production using Saccharomyces cerevisiae during simultaneous saccharification-fermentation (SSF)

Abstract

In this study, the effect of the photocatalytic (PC) pre-treatment with TiO2 during gelatinization (GE) stage in a simultaneous saccharification-fermentation process (SSF) of potato starch for bioethanol production was evaluated. Maximum amount of reducing sugars was 119.3, 114.6 and 104.8 g l-1 for PC→GE, GE→PC and reference (without PC), respectively while bioethanol concentration it increased gradually up to a maximum amount of 128.21, 106.74 and 85.91 g l-1 after 30 h, for PC→GE, GE→PC and reference (without PC), respectively. These results were consistent with the reducing sugars concentration, because bioethanol concentration increased slightly during 18–30 h of fermentation. Although enzymatic activity (ʋmax) for reactions was similar, in reference (without PC pre-treatment) it not promoted quick substrate conversion into ethanol, despite showing the higher affinity enzyme-substrate (Km). Considering traditional potato starch hydrolysis, PC pre-treatment shortened the reaction time of the biological reactions. Thus, the PC pre-treatment of potato starch for bioethanol production could be an environmentally feasible process without acid and alkali addition.