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Simultaneous non-thermal saccharification of cassava pulp by multi-enzyme activity and ethanol fermentation by Candida tropicalis

Paper ID Volume ID Publish Year Pages File Format Full-Text
22175 43259 2009 6 PDF Available
Title
Simultaneous non-thermal saccharification of cassava pulp by multi-enzyme activity and ethanol fermentation by Candida tropicalis
Abstract

Cassava pulp, a solid by-product from starch processing, is a promising and underused biomass that can be converted to biofuels and other value-added bio-products. In this study, an alternative cassava pulp saccharification process, which utilizes the multi-activity enzyme from Aspergillus niger BCC17849 and obviates the need for a pre-gelatinization step, was developed. The crude multi-enzyme composed of non-starch polysaccharide hydrolyzing enzyme activities, including cellulase, pectinase and hemicellulase act cooperatively to release the trapped starch granules from the fibrous cell wall structure for subsequent saccharification by raw starch degrading activity. A high yield of fermentable sugars, equivalent to 716 mg glucose and 67 mg xylose/g of cassava pulp, was obtained after 48 h incubation at 40 °C and pH 5 using the multi-enzyme, which was greater than the yield obtained from the optimized combinations of the corresponding commercial enzymes. The multi-enzyme saccharification reaction can be performed simultaneously with the ethanol fermentation process using a thermotolerant yeast Candida tropicalis BCC7755. The combined process produced 14.3 g/l ethanol from 4% (w/v) cassava pulp after 30 h of fermentation. The productivity rate of 0.48 g/l/h is equivalent to 93.7% of the theoretical yield based on total starch and cellulose, or 85.4% based on total fermentable sugars. The non-thermal enzymatic saccharification process described is more energy efficient and yields more fermentable sugar than the conventional enzymatic process. Furthermore, the process is applicable for production of various bio-products of economic importance.

Keywords
Aspergillus niger; Candida tropicalis; Cassava pulp; Ethanol; Non-starch polysaccharide hydrolyzing enzyme; Raw starch degrading activity
First Page Preview
Simultaneous non-thermal saccharification of cassava pulp by multi-enzyme activity and ethanol fermentation by Candida tropicalis
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Bioscience and Bioengineering - Volume 107, Issue 5, May 2009, Pages 488–493
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering