Single-Step Bioconversion of Unhydrolyzed Cassava Starch in the Production of Bioethanol and its Value-Added Products

• Main Authors: Azmi, Azlin Suhaida, Ngoh, Gek Cheng, Mel, Maizirwan, Hasan, Masitah
• Format: Book Chapter
• Language: English; English
• Published: InTech Co 2012
• Subjects: TP155 Chemical engineering; TP248.13 Biotechnology
• Online Access: http://irep.iium.edu.my/3849/2/Single-step-bioconversion-of-unhydrolyzed-cassava-starch-in-the-production-of-bioethanol-and-its-value-added-products.pdf; http://irep.iium.edu.my/3849/5/InTech-Single_step_bioconversion_of_unhydrolyzed_cassava_starch_in_the_production_of_bioethanol_and_its_value_added_products.pdf; http://irep.iium.edu.my/3849/; http://cdn.intechopen.com/pdfs/27349/InTech-Single_step_bioconversion_of_unhydrolyzed_cassava_starch_in_the_production_of_bioethanol_and_its_value_added_products.pdf

The global economic recession that began in 2008 and continued into 2009 had a profound impact on world income (as measured by GDP) and energy use. Since then the price of the energy supply by conventional crude oil and natural gas production has been fluctuating for years which has resulted in the need to explore for other alternative energy sources. One of the fastest-growing alternative energy sources is bioethanol, a renewable energy which can reduce imported oil and refined gasoline, thus creates energy security and varies energy portfolio. Global biofuel demand is projected to grow 133% by 2020 (Kosmala, 2010). However, the biofuel supply is estimated deficit by more than 32 billion liters over the same period and the deficit is worse for ethanol than biodiesel. Ethanol may serve socially desirable goals but its production cost is still remained as an issue. Extensive research has been carried out to obtain low cost raw material, efficient fermentative enzyme and organism, and optimum operating conditions for fermentation process. In addition to that, researchers have been trying to capitalize certain features of the plant equipment and facilities to increase the throughput of ethanol and other high value by products as well as to apply suitable biorefinery for the product recovery. At the same time, effort has been made to reduce utilities costs in water usage, cooling or heating, and also consumables usage via minimizing the effluent production. Aimed to provide an alternative means for ethanol production, this book chapter introduces a single-step or direct bioconversion production in a single reactor using starch fermenting or co-culture microbes. This process not only eliminates the use of enzymes to reduce the production cost but also yield added value by-products via co-culture of strains. Before further elaboration on this single-step fermentation, we will visit the conventional process, the substrate preparation and microbe used. By this way a clear picture of the differences between conventional process and the proposed single-step fermentation with the advantages and disadvantages of both processes will be discussed.