Biodegradation of cassava root sieviate with enzymes extracted from isolated fungi

Abstract

This study was carried out to investigate changes in proximate, sugars and cell wall components of cassava root sieviates (CRS) treated with extracted enzymes obtained from Aspergillus niger (An), Trichoderma viridae (Tv), Rhizopus stolonifer (Rs) and Mucor mucedo (Mm) applied on autoclaved CRS at 250ml/kg. Another treatment that had a commercial enzyme Roxazyme G2G (RG2G) as the degrading agent was prepared and the enzyme was applied at 150g/tonne as recommended by the manufacturer. At the end of the 7th day after enzyme application, the chemical analysis showed a higher bioavailability of nutrients in the degraded samples than the undegraded sample. Non starch polysaccharides (NSPs) in the CRS was negatively related to crude protein, ash and metabolisable energy (P<0.05) but positively related to crude fibre, pectin, neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), hemicellulose and cellulose content . The highest value of metabolisable energy (ME), Ash, crude protein and phosphorus were : 2807.81kcal/kg, 17.32,18.32 and 0.91 g/100g dry matter respectively; obtained when A.niger, T.viridae, A. niger and R. stolonifer enzymes were added respectively .The lowest values of crude fibre, pectin, NDF,ADF, ADL, hemicellulose and cellulose were: 4.82,3.52,30.74, 17.12, 3.74,13.71 and 14.46g/100g dry matter respectively obtained when enzymes extracted from A.niger , R. stolonifer, T. viride ,A. niger, R. stolonifer, M. mucedo and T. viride were applied . Results of levels of sugars (μg/ml) in undegraded CRS showed that glucose level increased by 72.40% (257.34 to 932.22), 67.18%(257.34 to 784.20), 53.75%(257.34 to 556.40), 50.13%(257.32 to 516.06) and 32.53%(257.34 to 381.43) when enzyme preparations from A. niger, T.viridae , R.stolonifer, M.mucedo, and Roxazyme G2G were applied on CRS for degradation respectively . Other sugars that were significantly (P<0.05) increased after biodegradation were galactose, fructose and sucrose. Significant (P<0.05) differences were also expressed in the mineral analysis. After biodegradation, the degraded CRS had better mineral bioavailability as there were improvements in the minerals quantity. The results revealed that the use of enzymes from the above named fungi and the commercial enzymes defiberised the CRS and hydrolyzed the cell walls and hence promoted better availability of energy, crude proteins and other nutrients which were hitherto unavailable. 

Keywords: Non-conventional ingredients, biodegradation, nutrient enhancement.