Model Study on Extraction of Both Fermentable Sugars and No-Structural Carbohydrate from Sweet Sorghum Using Diffusion Process

Sweet sorghum, a C₄ crop, is considered to be a potential bioethanol feedstock. The current roller-mills recovers only about 60-70% of the sugars from the stalk leaving up to 40% of sugars in the bagasse. In this work, fermentable sugars and no-structural carbohydrate were extracted from milled sweet sorghum bagasse and grains by diffusion process. Response surface methodology was applied to explore the relationship between the effect of the interaction of time, temperature and grain loading on starch-to-sugar efficiency and sugar recovery efficiency from sweet sorghum, as well as, to optimize the diffusion conditions. At an optimized time of 114.9 minutes, temperature of 95 °C and 22% grain loading, starch efficiency and sugar recovery efficiency of 96% and 98.5% were obtained.