Cassava Pulp Enzymatic Hydrolysate as a Promising Feedstock for Ethanol Production

Abstract

The aim of this study was to produce bioethanol from enzymatic hydrolysates of cassava pulp, a by-product of cassava flour manufacturing, using an alcohol-tolerant Saccharomyces cerevisiae strain. First, the best operational condition of the starch hydrolysis process was determined through a complete factorial design (2 4), with triplicates at the central point. The independent variables evaluated were: the concentrations of α-amylase (Termamyl 2X) and glucoamylase (AMG 300L) and both liquefaction and saccharification times. The most favorable hydrolysis condition in the assay was achieved using 0.517 mL AMG.g starch-1 and 0.270 mL Termamyl.g starch-1 , with liquefaction and saccharification times of 1 and 2 h, respectively. The broth obtained at this hydrolysis condition contained a high glucose concentration (160 g.L-1). Once the best reaction conditions were determined, fermentation tests were carried out in a 3 L bioreactor, in a batch system, at 30 °C, 100 rpm and pH 5.5, using 3 g.L-1 (dry biomass) of yeast as inoculum. After 24 h of fermentation, an ethanol concentration of 68 g.L-1 was obtained, with 0.48 ethanol yield and 2.83 g.L-1 .h-1 productivity. These results indicate the potential use of cassava pulp, a by-product of cassava flour industries in Brazil, as a raw material for bioethanol production.

Alternative Process for Production of Sweet Potato Distilled Beverage

“…In Brazil, the majority of bioethanol is produced by fermentation of sugarcane. However, other raw materials such as the ones rich in cellulosic fibers and starch might be used as well [1]. The sweet potato crop, a human food with good nutritional content, has great importance in animal feed and industrial production of flour, starch, and alcohol.…”