Identification of potential fermentation inhibitors in conversion of hybrid poplar hydrolyzate to ethanol

In the production of automobile fuel ethanol from biomass by dilute acid hydrolysis/fermentation process, degradation products from the hydrolysis substantially inhibit the bioconversion of sugar to ethanol. Majority of these inhibitors have not been previously identified due to the complexity of biomass hydrolyzate. This paper presents an analytical procedure for identification of biomass degradation products, which entails flash evaporation, anion exchange, chloroform and ethyl acetate extraction, HPLC and GC-MS analyses. More than 35 potential inhibitors to S. cerevisiae fermentation in dilute nitric acid hydrolyzates of hybrid poplar were identified by correlating the fermentability of the anion exchange treated and untreated hydrolyzate samples with their chemical compositions, and by chemical analysis of the regeneration eluate from the ion exchange resin saturated by the hydrolyzate.