Optimization of Reducing Sugar Production from Manihot glaziovii Starch Using Response Surface Methodology

Abdi Sebayang,Hwai Ong,Surya Dharma,Teuku Mahlia,Aditiya Bahar,Masjuki Hassan,Fitranto Kusumo,Arridina Silitonga

doi:10.3390/en10010035

Abdi Sebayang, Hwai Ong + Show 6 more

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https://doi.org/10.3390/en10010035

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Abstract

Bioethanol is known as a viable alternative fuel to solve both energy and environmental crises. This study used response surface methodology based on the Box-Behnken experimental design to obtain the optimum conditions for and quality of bioethanol production. Enzymatic hydrolysis optimization was performed with selected hydrolysis parameters, including substrate loading, stroke speed, α-amylase concentration and amyloglucosidase concentration. From the experiment, the resulting optimum conditions are 23.88% (w/v) substrate loading, 109.43 U/g α-amylase concentration, 65.44 U/mL amyloglucosidase concentration and 74.87 rpm stroke speed, which yielded 196.23 g/L reducing sugar. The fermentation process was also carried out, with a production value of 0.45 g ethanol/g reducing sugar, which is equivalent to 88.61% of ethanol yield after fermentation by using Saccharomyces cerevisiae (S. cerevisiae). The physical and chemical properties of the produced ethanol are within the specifications of the ASTM D4806 standard. The good quality of ethanol produced from this study indicates that Manihot glaziovii (M. glaziovii) has great potential as bioethanol feedstock.

Highlights

The use of alternative fuels has rapidly developed with the objective of reducing the impact of continuously burning non-renewable fossil fuel
The M. glaziovii starch was stored in a closed container in a refrigerator before the laboratory experiment was conducted
The results show that the substrate loading is the most important factor in reducing sugar production during hydrolysis

Summary

Introduction

The use of alternative fuels has rapidly developed with the objective of reducing the impact of continuously burning non-renewable fossil fuel. Bioethanol is a liquid resulting from fermentation of sugar and it is sourced from plants containing carbohydrates (starch) [2]. Microorganisms are used as enzymes in the fermentation process [3]. Bioethanol is widely used as a biofuel due to the following reasons: (1) bioethanol has high oxygen content and octane number; (2) bioethanol is non-toxic; and (3) bioethanol is environmentally friendly since it decreases pollutant emissions such as carbon monoxide, sulphur and nitrogen oxides [4,5]. Bioethanol has a number of disadvantages, Energies 2017, 10, 35; doi:10.3390/en10010035 www.mdpi.com/journal/energies

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