Accumulation Of Organic Acids In The Continuous Fermentation Affect The Self-flocculating Yeast Alcohol Waste Full-cycle Technology

Based on the analysis of ethanol fermentation metabolic pathways, several high boiling point by-products contained within the waste distillage discharged from continuous ethanol fermentation process using self-flocculating yeast strain SPSC01, including fumaric acid, malate, lactic acid and critic acid, were separated by HPLC. Furthermore, the effects of these organic acids on self-flocculating yeast cell growth and ethanol fermentation were investigated through adding these organic acids into the ethanol fermentation system, and the inhibition ethanol fermentation kinetics for self-flocculating yeast cell particles was developed as below.Finally, a theoretical model which can be used to predict the accumulation of all kinds of by-product for self-flocculation yeast cell ethanol fermentation process coupled with directly recycling use of waste distillage was proposed. The model parameter, waste distillage recycling times, can be deduced from experimental data. Malate, as demonstrated by-product, its steady-state concentration accumulated within the ethanol fermentation process was calculated and compared with its critical concentration which exerts obvious inhibition on self-flocculating yeast cell particle growth and ethanol fermentation. It was found that the inhibition of malate on self-flocculating yeast cell particle and ethanol fermentation was negligible.