O Adesanya, K Oluyemi, S Josiah, R Adesanya, L Shittu, D Ofusori, M Bankole, G Babalola
cassava, ethanol, simple reducing sugar
O Adesanya, K Oluyemi, S Josiah, R Adesanya, L Shittu, D Ofusori, M Bankole, G Babalola. Ethanol Production By Saccharomyces Cerevisiae From Cassava Peel Hydrolysate. The Internet Journal of Microbiology. 2007 Volume 5 Number 1.
Fungal isolates from rotten Cassava wastes were identified and screened for amylolytic activity.
In developing countries, there is a growing interest regarding the utilization of organic wastes generated by the food processing sector and through other human endeavours. This has led to a new policy of complete utilization of raw materials so that there will be little or no residue left that could pose pollution problems (6). The agriculture-based industries generate a significant amount of solid waste that, amongst other, include peels from Cassava, plantain, banana, oranges and straw from cereals. Rather than allowing these wastes to become solid municipal wastes, it is necessary to convert them to useful end-products. It is now realized that these wastes may be utilized as cheap raw materials for some industries or as cheap substrates for microbiological processes (7).
Much work has been carried out regarding the utilization of Cassava peels as substrates for microbial protein enrichment (5), increasing microorganism biomass (8) and on their use as food additives (9). However, the possibility of using Cassava peels for the production of ethanol has not been given much attention. This study was therefore initiated to explore the possibility of using Cassava peel as a substrate for producing ethanol.
Materials And Methods
Solid Cassava peel wastes were obtained from
Hydrolysis of Cassava peel
Twenty grams of Cassava peel flour was mixed with 500 ml of distilled water in two conical flasks and the mixtures were sterilized in an autoclave at 212 lb/sq for 15 min. Sterile distilled water was then added to each flask to a final volume of 1 liter and the flasks were plugged with sterile cotton wool to avoid contamination. After cooling, freshly harvested cells of
% Peel hydrolysis = [(Reducing sugars produced by growth – Reducing sugars in control) / Reducing Sugar in Control] x 100.
Determination of mineral composition of Cassava peel waste and of fermentation parameters
The proximate and mineral composition of Cassava peel waste was determined according to AOAC (10). Fermentation parameters,
Table 1 shows the changes in the percentage of crude protein, crude fibre, fat and ash yield of the fermented peeled cassava wastes inoculated with Aspergilus niger. The fermentation of the wastes with Aspergilus niger caused an increases in the percentage of crude protein and fats,and a decrease in the percentage crude fibre and ash.
Percentage hydrolysis increases with time, with a steady increased observed between day 4-6.
The concentration reducing sugar of uninoculated milled suspension remains at 0.45mg/ml throughout experiment, maximum level of simple sugar produced in the inoculated was 0.88mg/ml.
Average number of organism was estimated by multiplying count per plate by the dilution factor. The number of organisms increased in a logarithmic fashion reaching a maximum by the 4th day – 4.8 x 108 cells but gradually declined to 4.4 x 106 on the 7th day,which indicate degradative activity of the organism in milled Cassava.
The concentration of alcohol in control was 0.01% - 0.02%, the concentration of alcohol produced reached a value of 1.05 % by the 3rd day.
Inoculation of the cell-free Cassava peel hydrolysate with
Cassava peel is a source of cheap, degradable material for the production of simple sugars, which can be fermented by yeast to produce ethanol, as a cheap energy source for the use in our local communities. However, there is a need for further work to optimize the conditions for the production of simple sugar from the peels and to isolate a
The authors are grateful to Mr. Tony Okoh and the technical staff of the Department of Microbiology at Obafemi Awolowo University for their kind assistance when executing this project.