A study on the effect of bioadditives on alcohol fermentation

Abstract

The continuous depletion of the fossil fuel reserves and consequent escalation in their prices has stimulated an extensive evaluation of alternative technologies and substrates to meet the global energy demand. As a consequence, alternative sources of energy like methane, hydrogen and ethanol are increasingly being considered as potential substitutes. Hence in this present research an attempt has been made to optimize the ethanol production from sugar molasses. This study comprises with the general introduction about alcoholic fermentation, raw materials and addition of bioadditives to improve the process and their applications in industry. The molasses collected from Tiruttani Sugar mills, TamilNadu, India was sterilized and stored at 4oC in glass bottles. Saccharomyces cerevisiae was obtained from IMTECH Chandigarh, India and sub cultured. The physiochemical analysis of molasses was performed to determine pH, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), ammonia, nitrate, nitrite, calcium, magnesium and total carbohydrates with and without fermentation broth. Saccharomyces cerevisiae inoculated in 20% molasses containing 5 g/L of total sugars was reduced to 1.05 g/L and the yield of ethanol was 41.2 g/L. The nitrate and nitrite content were found to be 55 mg/L and 29 mg/L compared to 48 mg/L and 90 mg/L in control. Biological Oxygen Demand was found to be 114 mg/L when compared to unfermented broth of 240 mg/L. Chemical Oxygen Demand was found to be 310 mg/L in control whereas it decreased to 180 mg/L in fermented broth.The effect of various parameters on ethanol production such as inoculum size, pH, temperature, sugar concentration, substrate concentration, carbohydrate source and bioadditives were studied. It was found that optimal conditions for the production of ethanol were identified as pH 4.5, temperature 45oC, inoculum size 1.4 g/L, and molasses concentration 20%. Different carbohydrate sources such as glucose, sucrose, maltose, and fructose were used to analyse the maximum production o