ABSTRACT: The effect of heating on the vitamin C content of five choice vegetables was determined by redox titration with potassium iodate in the presence of potassium iodide. The results obtained in raw vegetables showed that pepper (61.56mg/100ml) has the highest vitamin C content while the least was in carrot (21.72mg/100ml). The vitamin C content of the vegetables analyzed were found to be in the order: Pepper > Green peas > Spinach > Pumpkin > Carrot. It was also observed that the heating time has significant effect on the vitamin C content of all the vegetables, as the heating time increases, the percentage loss of vitamin C increases too. The percentage loss of vitamin C in the vegetables ranged between (9.94-16.57%), (29.94-37.43%) and (49.91- 64.71%) at 5, 15 and 30 mins respectively. Of all the vegetables assayed pepper gave the highest percentage loss of 64.71% at 30 mins. Vitamin C is easily destroyed by excessive heat and water, as well as exposure to air. For retention of vitamin C in cooked foods, it is recommended that foods containing vitamin C be cooked as fast as possible with less heat and small amount of water.
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