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Appl. Sci. 2012, 2(4), 738-753; doi:10.3390/app2040738
Article

Ethanol Production from Waste Potato Mash by Using Saccharomyces Cerevisiae

1 and 1,2,*
Received: 16 July 2012; in revised form: 19 September 2012 / Accepted: 10 October 2012 / Published: 22 October 2012
(This article belongs to the Special Issue Renewable Energy)
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Abstract: Bio-ethanol is one of the energy sources that can be produced by renewable sources. Waste potato mash was chosen as a renewable carbon source for ethanol fermentation because it is relatively inexpensive compared with other feedstock considered as food sources. However, a pretreatment process is needed: specifically, liquefaction and saccharification processes are needed to convert starch of potato into fermentable sugars before ethanol fermentation. In this study, hydrolysis of waste potato mash and growth parameters of the ethanol fermentation were optimized to obtain maximum ethanol production. In order to obtain maximum glucose conversions, the relationship among parameters of the liquefaction and saccharification process was investigated by a response surface method. The optimum combination of temperature, dose of enzyme (α-amylase) and amount of waste potato mash was 95 °C, 1 mL of enzyme (18.8 mg protein/mL) and 4.04 g dry-weight/100 mL DI water, with a 68.86% loss in dry weight for liquefaction. For saccharification, temperature, dose of enzyme and saccharification time were optimized and optimum condition was determined as 60 °C-72 h-0.8 mL (300 Unit/mL) of amyloglucosidase combination, yielded 34.9 g/L glucose. After optimization of hydrolysis of the waste potato mash, ethanol fermentation was studied. Effects of pH and inoculum size were evaluated to obtain maximum ethanol. Results showed that pH of 5.5 and 3% inolculum size were optimum pH and inoculum size, respectively for maximum ethanol concentration and production rate. The maximum bio-ethanol production rate was obtained at the optimum conditions of 30.99 g/L ethanol. Since yeast extract is not the most economical nitrogen source, four animal-based substitutes (poultry meal, hull and fines mix, feather meal, and meat and bone meal) were evaluated to determine an economical alternative nitrogen source to yeast extract. Poultry meal and feather meal were able to produce 35 g/L and 32.9 g/L ethanol, respectively, which is higher than yeast extract (30.8 g/L). In conclusion, waste potato mash was found as a promising carbon source for ethanol fermentation with alternate nitrogen sources.
Keywords: enzyme hydrolysis; response surface method; bio-ethanol; Saccharomyces cerevisiae; fermentation; waste potato mash enzyme hydrolysis; response surface method; bio-ethanol; Saccharomyces cerevisiae; fermentation; waste potato mash
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Izmirlioglu, G.; Demirci, A. Ethanol Production from Waste Potato Mash by Using Saccharomyces Cerevisiae . Appl. Sci. 2012, 2, 738-753.

AMA Style

Izmirlioglu G, Demirci A. Ethanol Production from Waste Potato Mash by Using Saccharomyces Cerevisiae . Applied Sciences. 2012; 2(4):738-753.

Chicago/Turabian Style

Izmirlioglu, Gulten; Demirci, Ali. 2012. "Ethanol Production from Waste Potato Mash by Using Saccharomyces Cerevisiae ." Appl. Sci. 2, no. 4: 738-753.

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