EVALUATION OF PHYSIOCHEMICAL PROPERTIES AND PRESERVATION OF AFRICAN WALNUT (TETRACARPIDIUM CONOPHORUM)

The effect of processing methods on the nutritional, anti-nutritional and functional properties of African walnut was investigated. The proximate composition of African walnut (Tetracarpedium conophorum) on % wet basis showed protein (14.92), oil (45.84), fibre (1.14), ash (3.52) and carbohydrate (15.38). Evaluation of its anti-nutritional factors (mg/100g) revealed tannins (0.89), oxalate (1.28), phytic acid (3.105), trypsin inhibitors (1.84), saponin (985.0) and alkaloid (40.91) as being inherent to the edible nut. These constituents were significantly (p>0.05) decreased by cooking while toasting resulted in their increased concentrations but to a level found not harmful to the human body. The functional properties; water absorption capacity (1.68m/g), oil absorption capacity (1.06ml/g) and foaming capacity (6.2%) were generally improved by processing. Refrigeration, storage at room temperature (27-32°C) and addition of 0.01% ascorbic acid to walnut flour effectively extended the shelf life of the product.