Ethanol fermentation of uncooked cassava starch = 무증자 전분의 알코홀 발효

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A study on the process development for ethanol production from uncooked cassava starch was carried out. Optimization was conducted for the saccharification of uncooked starch by the combined actions of pectin depolymerase, $\alpha$-amylase, and glucoamylase. The conditions were : pectin depolymerase ; pH 4.5, $45\,^\circ\!C$, 2 hr, 0.3\%(w/w), $\alpha$-amylase ; pH 6.0, $60\,^\circ\!C$, 1 hr, 0.03\%(v/w), and glucoamylase ; pH 3.5, $60\,^\circ\!C$, 1 hr, 1.0\%(w/w). Simultaneous treatment of these three enzymes yielded better result than stepwise treatment of these enzymes, about by 8\%. From the enzymatic hydrolysis of uncooked starch under the optimized conditions, we achieved only 23\% of saccharification yield. For the increase of saccharification yield, several pretreatments such as acid and alkali steeping, irradiation, and sonification on the uncooked starch were introduced to the enzymatic hydrolysis. Among them, acid and alkali steeping showed good results for this purpose. Acid steeping as pretreatment of uncooked starch was affected by steeping time, steeping temperature, acid concentration, kinds of acid, and particle size of starch. The actual optimum conditions of acid steeping were : steeping of 30 mesh particles of starch in 0.5 N-HCl solution for 12 hr at $60\,^\circ\!C$, ratio of starch to steeping volume, 1 : 2(W:V). In this conditions, reducing sugar production by acid steeping was less than 6.8\% of total reducing sugar, which meant that acid steeping did not hydrolyze starch significantly, but changed the conformation of starch granules. The structural change of starch granules was observed by scanning electron microscope(SEM) and sedimentation experiment. When starch was steeped in acid solution, original truncated egg-shaped structure with smooth surface changed to more truncated one with rough surface and the size of starch granuled was reduced from about 20 um in diameter to half or much smaller than half. The saccharified broth contai...
Byun, Si-Myung변시명
한국과학기술원 : 생물공학과,
Issue Date
64499/325007 / 000831205

학위논문(석사) - 한국과학기술원 : 생물공학과, 1985.2, [ [x], 93 p. ]

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