Effect of Local Processing Techniques on the Nutrients and Anti-Nutrients Content of Bitter Cassava (Manihot Esculenta Crantz)

摘要

The effects of local processing techniques on the nutrients and anti-nutrients content of bitter cassava were investigated. Raw bitter cassava tubers were boiled to produce (Rogo), sundried to produce (chips), roasted to produce (roasted chips), fried to produce (Kuese), partially fermented and sun dried to produce (Elubo), fermented by submersion to produce (Akpu) and finally, fermented by solid state to produce (yellow and white Gari). All these locally processed cassava products were subjected to proximate, mineral and anti-nutrient analysis using standard methods. The result of the proximate showed that, raw bitter cassava is composed of 1.85% ash, 64.38% moisture, 4.11% crude fibre, 1.03% crude protein, 0.66% lipids and 30.88% total carbohydrate. Mineral analysis of the raw bitter cassava tuber contained 32.00mg/100g Calcium, 12.55mg/100g Magnesium, 1.38mg/100g Iron and 80.17mg/100g Phosphorous. Even though all processing techniques significantly expose more of the the mineral content, fermentation had highest effect. The anti-nutrients analysis showed that the raw peeled tuber contained 98.16mg/100g cyanide, 44.00mg/100g oxalate 304.20mg/100g phytate and 73.00mg/100g saponin. In general all the processing techniques showed a significant reduction of the phytate, oxalate and saponin content of the cassava. However, only fermentation, sun drying and garification were able to reduce the cyanide content of bitter cassava below the safe level (10mg/100g) recommended by Standard Organization of Nigeria. Yellow gari(with the addition of palm oil) showed low cyanide content (1.10 mg/100g) than white gari (3.51 mg/100g). This also emphasis that processing methods involving fermentation reduce cyanide and other anti-nutrients in the cassava to levels that are safe for consumption and should be widely practiced.