Bioethanol production from starchy wastes
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Date
2017
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CCSHAU
Abstract
Potato (Solanum tuberosum) is one of the most important agricultural crops for human
consumption and high amount is produced worldwide every year. Potatoes are starchy crops, which do
not require complex pre-treatments. Potato peel waste (PPW) is a zero value by product, which occurs
in big amounts after industrial potato processing and can range from 15-40 % of initial product mass,
depending on the peeling method. PPW has potential as a base for fermentation reactions because of
high starch content and could be utilized for bioethanol production. Sweet potato (Ipomoea batatas L.)
represents an important biomass resource for fuel alcohol production, because of its chemical
composition and high density of starch, compared to other forms of biomass, and thus premise as an
alternative bioresource for the production of ethanol through fermentation. Ethanol production from
potato and sweet potato peel wastes (SPPW) is relatively new topic and limited research has been
conducted about the utilization of these wastes.
In the present study, a total of 15 yeast isolates were obtained from soil and other sources like
fruits and vegetables, fermented foods etc. Out of these, 12 yeast isolates were screened for amylolytic
activity on starch agar medium. The zone index varied from 1.5 to 3.2 with yeast isolate YPO3
showing the maximum zone index (3.2). Only six isolates were selected for measuring the amylolytic
enzyme activity. The maximum enzyme activity was observed in YPO3 (181.54 U/ml). However, four
yeast isolates were used for optimization of conditions by SHF method for ethanol production from
potato and sweet potato peel wastes at different temperatures (30, 35 and 40°C), pH (5.0, 6.0 and 7.0)
and incubation period under stationary condition. The maximum bioethanol production was observed
from PPW and SPPW at temperature 35°C and pH 6.0 after 72 h of incubation under SHF. SSF of
PPW and SPPW was observed at temperature 35°C and pH 6.0 after 72 h of incubation period using
YPO3 and YPmp3. The maximum ethanol 2.83% and 3.14 % were observed by using YPO3 after 72 h
of incubation, whereas 3.75% and 4.62% were observed using Sacchromyces cerevisiae HAU-1 after
48 h of incubation from PPW and SPPW. The yeast isolates (YPmp3 and YPO3) showed maximum
ethanol production in SSF as compared to SHF.
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