CHANGES IN THE NUTRITIVE VALUES OF SOME NIGERIAN DIETS AFTER COOKING BY CERTAIN SOUTH EASTERN NIGERIAN TRADITIONAL METHODS

Abstract

A nutritional study was carried out on six commonly used traditional diets of South-Eastern Nigeria. In this study, the various recipes and the proportion of the foodstuffs used in the formulation of the peasant dietaries in South Eastern Nigerian were determined by survey. From these the six diets were prepared using the ordinary traditional cooking methods. Results on the nutrient composition of the raw and the cooked diets showed some losses of the vitamins, minerals and total fats as a result of cooking. Losses of total crude proteins and total ash were negligible. The effect of cooking on the nutritive values of the diets were evaluated by a rat assay method. The procedure involved the measurement of the operative biological value (B.V.), true digestibility (TD), protein efficiency ratio (PER), net protein utilization (NPU), net protein ratio (NPR), weight gains and the net dietary protein calories percent (NDP Cals %) for male and female rats fed on tho raw-mixed and cooked homogenized diets respectively. The studies on the rat also provided evidence of higher sensitivity of the male rats in dietary assays and of sex difference in response to the "Ekpan Nkukwo" diet (diet D5). The cooked diets showed higher TD, NPR, PER, NPU and NDP Cals% in the rats than the raw. Both forms of the six diets investigated showed lower BV, NPU, PER, NPR and NDP Cale % as compared with the control diet. The determination of the serum protein levels, serum protein patterns and of the total serum cholestorol levels in the experimental rats gave no evidence of the effect of traditional cooking on them. Comparison of the NDP Cals% of these diets with the FAO recommended scale of allowance of NDP Cals % for man at various physiological ages and states shows that peasant diets are inadequate especially for the most vulnerable groups- infants, growing children, pregnant women and lactating mothers. The quantitative estimation of the various amino acids in the raw-mixed and cooked diets was also carried out. Some losses due to cooking were observed. The implication of the various results are discussed.