Study on Fermentation Kinetics for Accelerated Production of Bioethanol from Glucose, Sucrose and Molasses

Abstract

Currently, fermentation is the only available pathway for converting carbohydrates to ethanol and it is often time-consuming. The focus of the current research is to expedite ethanol production from carbohydrates using Saccharomyces cerevisiae. This study evaluated fermentation using a high-speed stirrer (ultraturrax) where glucose was the model carbohydrate. The reaction kinetics of fermentation was evaluated using 13C NMR spectroscopy. The effect of stirring speed on the kinetics of glucose fermentation was studied and two times enhancement in the rate of fermentation was observed using an ultraturrax (3.80 ± 0.40 × 10-5 s-1) compared to the incubation (1.90 ± 0.71 × 10-5 s-1) at 30°C. The acceleration of the fermentation was also observed using other carbohydrates such as sucrose and molasses. We report the effect of varying a few parameters such as: stirring speed, the effect of shelf-life of yeast, pH of the broth, and effect of activated carbon on the fermentation kinetics. The optimum pH range for the fermentation reaction was found to be 4-6.8. Yeast with a six-month shelf-life was found to slow down the fermentation reaction by 5.6 times relative to fresh yeast (up to one month). Our results indicate an efficient method for bioethanol production from carbohydrates.