Effects of pH on Ethanol Production from Sago Starch at Very High Gravity Fermentation

Nurul Hafiza Al Abadiyah, Ralmi (2014) Effects of pH on Ethanol Production from Sago Starch at Very High Gravity Fermentation. [Final Year Project Report] (Unpublished)

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Abstract

Nowadays, Very High Gravity (VHG) fermentation become an interesting subject to be studying as this type of fermentation will help us in producing more than 15% (v/v) ethanol compared with 10-12% (v/v), the normal range for most distilleries. Very High Gravity (VHG) fermentation usually was done by fermenting sugar in excess 270 g/l. In this study, Hydrolysed Sago Starch (HSS) was used as glucose sources by undergoing two important steps which are liquefaction and saccharification. After that, glucose produced was fermented by Saccharomyces cerevisiae at Very High Gravity (VHG) fermentation. As sugar concentration increases, the yeast is exposed to severe conditions such as high osmotic pressure, increased product inhibition and nutritional limitations, which seriously affect fermentation process. Three different pH used in this study, were pH 4.5, pH 5.0 and pH 5.5. The most suitable pH was pH 5.0 because the highest concentration of ethanol was achieved at 112.74 g/L and the lowest glucose left was at 71.90 g/L. Bioethanol was managed to be produced from HSS through batch fermentation process by S. cerevisiae at temperature 30°C in 150 mL working volume.

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