3-29: Starch hydrolysis evaluation for the production of fermentable sugars

Development of a fermentation process using economic carbon sources is extremely important for commercial scale biofuel production. Profitability of the fermentation process depends mainly on the pretreatment given to the raw materials. In this work, the best acidic and enzymatic hydrolysis conditions for yucca and malanga starch were studied through a statistical study in order to obtain the highest yield of fermentable sugars. An analysis of variance study (ANOVA) and a 2³ factorial design were performed to study three important factors in acidic hydrolysis: temperature, H₂SO₄ concentration and time. We observed with a 95% of confidence, that temperature is a factor with an important effect over hydrolysis and that the best hydrolysis conditions for the yucca and malanga starch were: 5% H₂SO₄, 5 h and 95°C; obtaining yields of 0.47 gr glucose/gr of yucca flour and 0.52 gr glucose/gr of malanga flour. A 2³ central design and a response surface analysis were performed in order to establish the best conditions for the enzymatic hydrolysis of yucca and malanga flour starch with α-amylase and amiloglucosidase in synaeresis. Three of the factors considered important for the reaction were studied: temperature, pH and hydrolysis time. Response surface analyses showed that the response was minimal in the central points for both tubers and that, with a 95% confidence, the best conditions for the enzymatic hydrolysis were: 73.6°C, pH 4.08 and 3 h, with a yield of 0.27 g glucose/g of yucca flour and 0.16 gr glucose/gr of malanga flour.