Hossein Vaheed - Department of Chemistry, E.M.U. Magusa, Turkey
S. Mohammad Mousavi - Department of Chemical Engineering, Tarbiat Modares University, Tehran, Iran
S. Abbas Shojaosadati - Department of Chemical Engineering, Tarbiat Modares University, Tehran, Iran
Hasan Galip - Department of Chemistry, E.M.U. Magusa, Turkey

Regarding some reported antimicrobial properties of tannins; Zymomonas mobilis was used to obtain ethanol from tannin-reduced carob pod extract (TR-CPE). Culture of ۵۰ mL volume containing ۷.۵ g sugar at pH ۵.۵ and ۰.۰۳ g bacterial inoculums with shaking at ۸۰ rpm was used. Using response surface methodology (RSM), the maximum ethanol concentration of ۵.۳۴ % w/v (higher than that reported earlier, ۴.۰۱% w/v) was obtained at the optimized addition levels of yeast extract, peptone, and fermentation time; ۰.۱۳ g, ۰.۶۲ g, and ۴۳.۷۸ h, respectively. Carob pods extract (CPE) containing ۶۲.۲۳ gl-۱ sugar was treated with ۳ gl-۱ gelatin to decrease its tannin content by ۵۷.۸۷ %. Sugar loss was not observed during gelatin treatment. The results revealed that there was no significant difference in ethanol production, yield, and productivity between TR-CPE and non-TR-CPE. In conclusion, tannin showed no inhibiting effect to maximum ethanol production by Zymomonas mobilis.

Carob pod extracts, Ethanol production, Tannin-reduced, Zymomonas mobilis