The Effect of Cooking Time on The Vitamin C, Dietary Fiber and Mineral Compositions of Some Local Vegetables.
AbstractThe effect of cooking time was investigated on green Leafy vegetables, Telifaira occidentalis (FP), Vernonia amygdalina (BL), Telinum fruticosum (WL) and Spinacia oleracea (SP) obtained from Tudun Wada market, Zaria, Nigeria. The vegetables were analyzed using standard analytical methods to evaluate vitamin C, crude fiber, minerals and heavy metals composition at different cooking time (T1 for fresh, T2 boiled for 5 minutes, T3 boiled for 15 minutes, T4 boiled for 20 minutes, T5 boiled for 25 minutes and T6 boiled for 30 minutes). The results from the study indicated that fresh Spinacia oleracea had the highest content of vitamin C (15.34mg/100g) while Telifaira occidentalis had the highest content of crude fiber (12.2 g/100g). Vernonia amygdalina had the highest iron (12.9 ppm), while zinc, cadmium and chromium are high in Spinacia oleracea (with 2.53 ppm, 2.62 ppm and 1.86 ppm respectively). Results also showed an overall decrease in vitamin C, crude fiber, minerals and heavy metal level with increased cooking time. The decrease was noticed when the vegetables are cooked above 15 minutes. The study revealed that the four green leafy vegetables are rich in vitamin C, crude fiber and minerals and should be consumed in reasonable quantity in our diet but should not be cooked beyond fifteen minutes