Abstract:
The fermentation of cassava peels to reduce cyanide and the pollution caused on the soil and water of cassava processing environment were investigated. Microorganisms were involved in the natural fermentation of cassava peels to produce linamarase for the breakdown of cyanogenic glucosides as well as improve protein content during under water fermentation of grated wet and dried cassava peels at ambient temperature of 28 ± 2oC and 75 ± 5% relative humidity. Corynebacterial manihot, Lactobacillus plantarum, Sacharomyces exiguus and Geotrichum candidum were isolated from waste water obtained during fermentation of garri. Standard analytical methods were used to monitor the fermentation for linamarin breakdown and free (residual) cyanide production. Linamarin decreased with increase in fermentation time and the lowest value of linamarin was observed at 96 hours by the mixed microbes of bacteria and yeasts (wet {20.11 mg HCN/kg} and dried samples {72.94 mg HCN/kg}). Residual cyanide increased during fermentation; however, there was no ordered pattern in the increase. Total titratable acidity increased with increase in time of fermentation. The mash fermented by Lactobacillus spp. had the highest values of titratable acidity of 22.26 % and11.60% at the end of fermentation for both wet and dried samples respectively while their pH values reduced as the fermentation period increased. Protein content of mash fermented by Lactobacillus spp. and naturally fermented peels had the highest value (21.60 and 20.58 mg/g/dry matter respectively) for both wet and dried samples. The carbohydrate content of the Lactobacillus spp. fermented mash (48.13 mg/g/dry matter) was lower than the values obtained from the mashes fermented by other isolates, in the wet sample. Cassava peels fermented for more than 96 hours can be recommended as alternative animal feed. The research work on cassava processing environments also revealed that the well water, top and subsoil were rich in soluble cyanide. Moreover, the nitrogen, phosphorus and potassium content of the cassava processing top and subsoils were very high; nevertheless, the organic matter content of the soil was very low.
