Fed-Batch Strategy Optimization for Ethanol Production Using Indigenous Co-Culture From Whey-Molasses Mixture
摘要
Whey, a lactose rich by-product of the dairy industry, is often discarded untreated, leading to environmental concerns. Valorizing whey in conjunction with molasses for ethanol production provides an effective and sustainable solution. Ethanol is a renewable energy resource formed from starch-rich biomass like sugarcane, corn, wheat and is in high demand as a biofuel. The present study investigated the potential of whey and molasses for ethanol production using fed-batch method. Co-inoculation technique with Kluyveromyces marxianus (OQ520116) to ferment whey and Saccharomyces cerevisiae (MK680910) for a secondary fermentation of the whey-molasses wort was performed. Optimized conditions for the primary fermentation were 32 °C, 9% inoculum size, over 4.5 days, while secondary fermentation conditions were set to 31 °C, 20% molasses concentration, and a 6.5% inoculum size, for 4.5 days. The primary fermentation yielded 1.79% (v/v) or 14.13 g/L of ethanol from whey, with residual total sugars at 1.65 g/100 mL and reducing sugars at 0.025 g/100 mL. Secondary fermentation achieved 10.5% (v/v) or 82.85 g/L ethanol from the wort, leaving 2.09 g/100 mL and 0.71 g/100 mL of total and reducing sugars, respectively. Double distillation of the wort produced 39.48% ethanol. Upscale validation for industrial setting at a 7L scale yielded 10.95% ethanol after fermentation and 42.6% after distillation. Fourier transfer infrared spectroscopy up to 4200 cm−1 showed a high concentration of alcohol, carbonyl and amide-related functional group peaks indicative of ethanol presence. This study underscores the effectiveness of using K. marxianus and S. cerevisiae co-culture in optimizing ethanol production from renewable biomass sources, whey and molasses, offering a viable and economically sustainable approach for ethanol generation.