Very High Gravity Fermentation Using Sweet Potato for Fuel Ethanol Production

Abstract

Sweet potato (Ipomoea batatas) was a wildely planted root crop in most area of China and considered as a good feedstock for fuel ethanol production. Very high gravity ethanol fermentation technology exhibited promising industrial application for advantages including productivity improvement, polluted water output reduction and energy consumption saving. In this study very high gravity liquefied sweet potato mash containing 260 g/kg glucose (after fully saccharified) was used for fuel ethanol fermentation. 0.8 g/kg (dry matter weight) was proved as the optimum glucoamylase adding dosage in simultaneous saccharification and fermentation. Datas analysis indicated that the osmotic pressure was controlled strictly exhibited by high growth rate of yeast and high rate of ethanol formation comparing with other dosages, and 119.78 g/kg (15.07 %, v/v) ethanol equivalent to 90.16 % of theoretical yield was achieved in 64 hours.

Evaluation of sweet potato for fuel bioethanol production: hydrolysis and fermentation

“…SSF has been considered a good choice to reduce the osmotic pressure caused by high initial concentration of dissolved sugars in batch ethanol fermentation under VHG condition (Cao et al 2011; Shen et al 2011; Srichuwong et al 2009; Zhang et al 2011), and the feedback inhibition that the AMG could present by the presence of high concentrations of glucose (Cao et al 2011; Mojović et al 2006). In a SSF, the temperature and pH are more favorable for the yeast growth (~ 30°C) rather than for the AMG activity.…”

“…An effective ethanol production process is one where the amount of water added is minimal, since more energy will be required to remove it at the end of the process if the final ethanol concentration is low (Cao et al 2011; Shen et al 2011). High ethanol concentration can be reached if the fermentation broth contains high fermentable sugar concentration.…”