Abstract: Rice bran has been abandoned as agricultural waste for million tonnes per year in Thailand, therefore they have been proposed to be utilized as a rich carbon source in the production of bioethanol. Many toxic compounds are possibly released during the pretreatment of rice bran prior the fermentation process. This study aims to analyze on the availability of toxic compounds and the amount of glucose obtained from 2 different pretreatments using sulfuric acid and mixed cellulase enzymes (without and with delignification/ activated charcoal). The concentration of furfural, 5- hydroxymethyl furfural (5-HMF), levulinic acid, vanillin, syringaldehyde and4-hydroxybenzaldehyde (4-HB) and the percent acetic acid were found to be 0.0517 ± 0.049 mg/L, 0.032 ± 0.06 mg/L, 21074 ± 1685.62 mg/L, 126.265 ± 6.005 mg/L, 2.89 ± 0.30 mg/L, 0.37 ± 0.031mg/L and 0.72% under the pretreatment process without delignification/ activated charcoal treatment and 384.47 ± 99.02 g/L, 0.068 mg/L, 142107.62 ± 8664.6 mg/L, 0.19 mg/L, 5.43 ± 3.29 mg/L, 4.80 ± 0.76 mg/L and 0.254% under the pretreatment process with delignification/ activated charcoal treatment respectively. The presence of high concentration of acetic acid was found to impede the growth of Zymomonas mobilis strain TISTR 551 despite the present of high concentration of levulinic acid. Z. mobilis strain TISTR 551 was found to produce 8.96 ± 4.06 g/L of ethanol under 4 days fementation period in biofilm stage in which represented 40% theoretical yield.
Abstract: Ethanol has been known for a long time, being
perhaps the oldest product obtained through traditional biotechnology
fermentation. Agriculture waste as substrate in fermentation is vastly
discussed as alternative to replace edible food and utilization of
organic material. Pineapple peel, highly potential source as substrate
is a by-product of the pineapple processing industry. Bio-ethanol
from pineapple (Ananas comosus) peel extract was carried out by
controlling fermentation without any treatment. Saccharomyces
ellipsoides was used as inoculum in this fermentation process as it is
naturally found at the pineapple skin. In this study, the capability of
Response Surface Methodology (RSM) for optimization of ethanol
production from pineapple peel extract using Saccharomyces
ellipsoideus in batch fermentation process was investigated. Effect of
five test variables in a defined range of inoculum concentration 6-
14% (v/v), pH (4.0-6.0), sugar concentration (14-22°Brix),
temperature (24-32°C) and time of incubation (30-54 hrs) on the
ethanol production were evaluated. Data obtained from experiment
were analyzed with RSM of MINITAB Software (Version 15)
whereby optimum ethanol concentration of 8.637% (v/v) was
determined. The optimum condition of 14% (v/v) inoculum
concentration, pH 6, 22°Brix, 26°C and 30hours of incubation. The
significant regression equation or model at the 5% level with
correlation value of 99.96% was also obtained.