Huynh Xuan Phong * , Nguyen Ngoc Thanh , Pham Thieu Quan and Ngo Thi Phuong Dung

* Corresponding author (hxphong@ctu.edu.vn)

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Abstract

Bioethanol is an environmentally friendly fuel and renewable source in many industrial applications. Cocoa pod is an abundant agro-waste source and can be used for bioethanol production because this lignocellulosic material has high content of cellulose. The aim of this study was to investigate the ability for bioethanol production from cocoa pod hydrolysate. Four strains of Saccharomyces cerevisiae (2.1, B3, D3, D4) were examined for bioethanol production from cocoa pod hydrolysate with the initial inoculation levels at 102, 104, 106, 107 cells/mL. The fermenting medium was tested with the reducing sugar concentration in a range of 5.0, 6.0, 7.0, and 8.6% (w/v) and pH value at 4.5, 5.0, 5.5 and 6.0. The fermentation conditions were designed at different temperatures (25, 30, 37°C) and times (3, 5, 7, 9 days). The results showed that the suitable yeast strain for ethanol fermentation was S. cerevisiae D3 with the inoculum level of 106 cells/mL. The ethanol concentrations of 4.14-4.19% (w/v) were achieved after 9 days at 30°C from cocoa pod hydrolysate contained 8.6% (w/v) of reducing sugar with initial pH at 5.5, the sugar consumption efficiencies were 97.54-97.56%. These outputs indicated the promising feasibility of bioethanol production from such waste material source of cocoa pods.
Keywords: Cocoa, cocoa pod hydrolysate, ethanol fermentation, Saccharomyces cerevisiae, Theobroma cacao

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