EXTRACTION OF FAT FROM AFRICAN NUTMEG (PYCNANTHUS ANGOLENSIS) SEEDS USING CELLULASE FROM ASPERGILLUS NIGER

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ABSTRACT

The production and application of partially purified cellulase from Aspergillus niger on Pycnanthus angolensis seeds to enhance fat recovery was evaluated. The production of the enzyme from A. niger was carried out using the solid state fermentation and maize bagasse as the only carbon source. Optimization of the enzyme production revealed that maximum cellulase secretion was on day four and the optimum substrate concentration was 25%. The cellulase was partially purified using ammonium sulphate precipitation. The optimum temperature and pH of the dialyzed enzyme were 50oC and 6.5 respectively while the specific activity was 33.94 U/mg and protein content was 9.84 mg/ml. The P. angolensis seed was dried to constant weight in an oven at 60ᵒC and then pulverized using a mechanical grinder. It was then sieved into two particle sizes 1.0 and 1.4 mm. Each of the two particle sizes were further divided into three portions of 100 g each. The first portion was treated with the partially purified enzyme. The second portion was treated with distilled water while the third portion was without any treatment and served as the control. The samples were dried and extraction of the fat was carried out using n-hexane as the solvent. The enzyme-treated, water-treated and untreated samples recorded fat yield of 88.2%, 76.8% and 72.7% respectively for the 1.0 mm particle size. Also, the enzyme-treated, water-treated and untreated samples recorded fat yield of 83.9%, 74.9% and 68.3% respectively for the 1.4 mm particle size. A number of physicochemical parameters were considered to assess the nature of the oil. In the physicochemical analysis, the enzyme-treated sample showed a significant (p˂0.05) increase when compared to the water-treated sample and the untreated sample in the acid value, free fatty acid and saponification value. No significant (p˂0.05) difference was observed in the iodine value. However, the peroxide value, specific gravity, refractive index and viscosity of the fat showed significant (p˂0.05) decrease in the enzyme-treated sample. The colour of the fat was reddish-brown and consistent in all the samples. The study indicated that treating the seeds of P. angolensis with cellulase and reduction in particle size of the seeds improved both yield and quality of the fat.