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A study was carried out on yeast fermentation of carica papaya (pawpaw) agricultural waste using dried active baker's yeast and brewer's yeast strain (Sacchromyces cerevisiae). The pawpaw considered as an agricultural waste was the tapped ripe pawpaw fruit harvested after the tapping of papain. Effect of different yeast strains on the percentage yield of ethanol was investigated. The effects of yeast concentration, saccharification and different nutrient supplements as they relate to the optimization of the ethanol yield were also carried out. The fermented pawpaw yielded ethanol contents of 3.83 to 5.19% (v/v). The reducing sugar in the pawpaw was determined before and after saccharification. The reducing sugar was highest after 48 h of saccharification using Aspergillus niger. The value recorded was 7.6 to 13.6 g/100g. Brewers yeast gave a higher ethanol yield than bakers yeast. Saccharification for 48 h coupled with nutrient supplements significantly increased the ethanol yield.

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Lactic acid bacteria produce lactic acid as the major end product during sugar fermentation. This study was carried out to isolate lactic acid bacteria (LAB) from pupuru; a staple cassava food. The result of the bacterial count indicated that the count ranges from 3.1 × 104 CFU/g to 8.7 × 104 CFU/g. Base on the Gram reaction, microscopic morphology and biochemical characteristics, the isolated LAB were identified as Pediococcus halophilus, Lactobacillus casei, Lactobacillus brevis, and Lactobacillus fermentum. Analysis of the percentage of occurrence of the lactic acid bacteria indicated that Lactobacillus casei (50.0%) was the most dominant LAB, P. halophilus, Lactobacillus brevis, L. fermentum were least occurring (16.7%). The amylase enzyme index showed that P. halophilus had no enzyme index while L. casei and L. fermentum had enzyme index of 4.00 mm while L. brevis had an enzyme index of 3.00 mm. Of the LAB isolated, only L. casei (0.064 µg/mL) had invertase activity. L. fermentum (0.099 µg/mL) and L. casei (0.08 µg/mL) showed considerable effect in the production of amylase. The result of this study indicated that Lactobacillus brevis, L. casei, and L. fermentum will be a viable addition in the amylase production industries while L. casei could be investigated further for enhancement in enzyme production.

A study on yeast fermentation of bitter kola pod( agricultural waste) was carried out using dried active bakers' yeast (Saccharomyces cerevisiae)and brewer's yeast (Saccharomyces carlsbergensis) Effects of saccharification using Aspergillus niger and different treatments on the waste as they relate to the optimization of the ethanol production were investigated. The reducing sugar in the waste was increased after 24-48 hours of sacharification using Aspergillus niger, fresh bitter kola waste recorded 4.4 -8.0g/100g of the waste, while the partially fermented bitter kola waste gave the value in the range of 5.6 -6.8g/100g. Baker's yeast gave a higher ethanol yield than Brewer's yeast. Different treatments of bitter kola pod revealed that addition of nutrient supplement enhanced the ethanol yield; however, 48 hours of saccharification significantly improved the ethanol yield at p ≤ 0.05.