Abstract
Pretreatment technologies have been developed to increase the bioconversion rate of biomass into fermentable sugar. The objective of this research was to investigate extrusion with thermostable α-amylase injection at different melt temperatures 95, 115 and 135°C on functional properties, ethanol content and conversion (%) of corn starch extrudates. Saccharomyces cerevisae (ATCC 24858) was used for ethanol production. In the present study, significant increase in ethanol production was achieved by the injection of thermostable α-amylase during extrusion process at melt temperature 115°C. The data clearly showed that thermostable α-amylase injection gave significantly increased (p<0.05) ethanol content at melt temperature 115°C from fermentation period from 24 to 48 hr. Industrial bio-ethanol production by direct fermentation following extrusion with thermostable α-amylase injection and omitting the saccharification step will be very effective in reducing ethanol production costs in countries like U.S. Therefore, ethanol production from extruded corn starch with thermostable α-amylase injection is a significant finding that could be applied to improve bioconversion rate for ethanol production.
Highlights
Starch-containing crops form an important constituent of the human diet
Corn starch provided by Samyang Genex Co. (Korea) was used for extrusion
Significant increase in ethanol production was achieved by the injection of thermostable α-amylase injection during extrusion process at melt temperature 115°C
Summary
Starch-containing crops form an important constituent of the human diet. Besides the use of the starch-containing plant parts directly as a food sources, it is used as chemical or enzymatic processes into a variety of different products such as starch hydrolysates, glucose syrups, fructose, starch of maltodextrin derivatives, or cyclodextrins. Few plants are able to produce industrial starch. The major industrial starch sources are maize, tapioca, potato, and wheat. Sugar sources such as starch and cellulose are potential candidates for ethanol production, biodiesel, and organic chemicals. Ethanol is produced through fermentation of various grains (i.e. corn, sorghum, barley, and wheat) and sugar crops (i.e. sugar cane, sugar beets and sweet sorghum) with CO2 as a by-product. Several factors have been suggested to be responsible for the low starch digestibility [1]
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