| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 104 === The demand for fossil fuels has significantly increased since the beginning of industrial revolution. Petroleum, one of the most important types of fossil fuel, is predominantly being used as car’s fuel. Fossil fuel dependence leads to the increase of greenhouse gas, resulting in more severe greenhouse effect and global warming. In order to lessen the amount of air pollution due to fossil fuel burning and to alleviate the energy crisis, many countries began to develop alternative fuels. Bioethanol is one of the high efficient and low environmental impact bioenergy sources. The raw materials that produce bioethanol can be divided into sugar, starchy and lignocellulose materials. Using starchy materials for bioethanol production have many advantages, such as rich in fermented sugar, high efficiency of ethanol production, simple operation and so on. Most of starchy materials are foods and have lot of controversies. Second generation bioethanol are using lignocellulosic materials. These materials have some properties, such as harsh hydrolysis conditions, fewer fermented sugar, and lot of inhibition substances. If we can find a kind of starchy agricultural resource, it can compensate for the disadvantages of both.
Taro is one of the most important crops in Taiwan and annual output about 40,000 tons, which serves as main ingredient of different types of food products such as pastries, snacks, and dessert. In this study, we used taro agricultural resource (TAR), which is provided by taro pastries factory to perform our experiment. The received TAR was mainly composed of taro’s skins that contain many starch residues. We pretreated and enzymatically hydrolyzed TAR. Various alternative nitrogen sources were evaluated as substitute nitrogen source of yeast extract for producing more economic and environmental friendly medium for ethanol production. Subsequently, we are going to discuss about the factors of modification medium, such as TAR loading amount, ions concentration, inoculum and medium filtration. The modification medium is followed by using thermotolerance yeast K21 to separate hydrolysis fermentation (SHF) and simultaneous saccharification fermentation (SSF) under different temperature. Our ultimate goal is scale-up to 5L bioreactor to make sure of conditions can produce ethanol efficiently by using TAR. The flask scale result showed the optimizing medium was using 170 g/L TAR which can hydrolyze about 100 g/L glucose and added 9 g/L CGM and salt without filtration. The optimizing medium was inoculated 5% K21 under 40oC by SSF can carry out the maximum ethanol concentration (48.98g/L) and productivity (2.23g/L/h). The result of maximum ethanol concentration and productivity were 43.78 g/L and 2.19 g/L/h, respectively in 5L bioreactor under the optimizing condition.
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