Enzymatic hydrolysis of cassava starch for production of bioethanol with a colombian wild yeast strain

Abstract

A hidrólise enzimática do amido de mandioca para produção de xaropes de glucose foi avaliada usando alfa-amilase de Bacillus licheniformis e glucoamilase de Aspergillus níger. Também, uma mistura enzimática composta de α-amylase de Aspergillus kawachi e glucoamilase de Aspergillus níger foi testada. As condições da enzima para a hidrólise do amido foram otimizadas por um planejamento fatorial experimental (3 3 ×2) usando como variáveis a concentração do substrato, a relação enzima/ substrato e o tempo de reação. As condições ótimas de reação com 100 g de amido per L foram: α-amilase pH 5,0, 80 °C e 130,5 U g -1 de amido; glucoamilase pH 4,5, 70 °C e 81,5 U g -1 de amido. Adicionalmente, as condições ótimas da mistura enzimática foram pH 4,5, 46 °C e 16,4 U g -1 de amido. Finalmente, a produção de álcool usando xaropes de glucose a partir do amido hidrolisado enzimaticamente foi realizada usando uma cepa selvagem de Candida sp isolada do caldo de cana de açúcar, obtendo produtividades em etanol volumétrico em torno de 1,Enzymatic hydrolysis of cassava starch for producing glucose syrups was evaluated using alpha-amylase from Bacillus licheniformis and glucoamylase from Aspergillus niger. Moreover, an enzyme mixture of α-amylase from Aspergillus kawachi and glucoamylase from Aspergillus niger was tested. Enzyme conditions for starch hydrolysis were optimized by a factorial experimental design (3 3 ×2) using as variables substrate concentration, enzyme/substrate ratio and time reaction. Optimal enzyme reactions with 100 g of starch per L were: α-amylase at pH 5.0, 80 °C and enzyme dosage of 130.5 U g -1 of starch; and glucoamylase, pH 4.5, 70 °C and enzyme dosage of 81.5 U g -1 of starch. Additionally, optimal conditions for the enzymatic mixture were pH 4.5, 46 °C, and enzyme dosage of 16.4 U g -1 of starch. Finally, alcohol production using glucose syrups from enzymatically-hydrolyzed starch was carried out with a wild strain of Candida sp isolated from sugar cane juice, obtaining volumetric ethanol productivities around 1.8-3.2 g L -1 h -1 .

Simultaneous cold hydrolysis and fermentation of fresh sweet potato

“…The conventional conversion of starch to glucose requires a two-step process: liquefaction and saccharification. During liquefaction, gelatinization of starch is promoted by applying high temperature (around 90 C) in excess of water, converting semi-crystalline starch granules to amorphous conformation, which is more susceptible to enzymatic hydrolysis [9,10]. This process is energy-intensive, increasing significantly the production cost of starch-based ethanol.…”

Utilization of Iles-Iles and Sorghum Starch for Bioethanol Production

“…The ffect of glucoamylase enzyme concentration was also examined by Shewale & Pandit (2009) which obtained an optimal concentration at 0.052% v/w for sorghum starch. Ruiz et al (2011) used a variable 16.4, 37.8 and 81.6 U/g in the process of saccharification for cassava which obtained an optimum conditions for glucoamylase enzyme at 81.6 U/g. This suggested that if the addition of glucoamylase enzyme was too low or too high therefore it caused saccharification process was not optimal.…”

Efficient Process Development for Cellulosic Ethanol Fermentation from Cassava Pulp

“…1B. The mixture was mixed with a thermostable -amylase (Termamyl ® , Novozymes, Denmark), and increased the temperature to 90 C for 1 h. Subsequently, a gluco-amylase (Spirizyme Fuel ® , Novozymes, Denmark) was added, and the temperature of the solution was decreased to 70 C for 2 h [6]. The slurry was then pressed through a filter bag in order to separate liquid from solid.…”