Usage of soluble soy protein on enzymatically hydrolysis of apple pomace for cost-efficient bioethanol production

In this study, bioethanol production and the effect of soluble soy protein on enzymatic hydrolysis of apple pomace as a cheap additive investigated. For this purpose essential parameters for fermentation such as biomass loading (5%, 10%, 20%), different media compositions (the whole slurry and washed fraction), enzyme loadings (15, 30, 60, 120 FPU/g substrate), fermentation time (24, 48 and 72 h) and soluble soy protein concentrations (20, 40, 80, 160 mg/g cellulose) were optimised. The positive effect of soluble soy protein on enzymatic hydrolysis and bioethanol production was observed. The highest sugar concentration without soy protein addition was found as 155 g/L in the presence of 120 FPU and S. cerevisiae produced 52.4 g/L bioethanol. On the other hand, when the enzyme concentration decreased two times (60 FPU) and supplemented with 80 mg/g cellulose soluble soy protein, sugar concentration increased to 176 g/L, and S. cerevisiae produced 53.1 g/L bioethanol. This study indicates that apple pomace is a suitable raw material for bioethanol production, and soluble soy protein can be evaluated for more economical bioethanol production.