[Effect of different cooking methods on the content of vitamin C in some vegetables]

ABSTRACT

Vitamin C is considered as the indicator of process severity, because of its high sensitivity to heat. There is an inverse relationship between vitamin C retention and the process severity. The aim of this study was to determine the effect of different common cooking methods on process severity and decrease amount of vitamin C in some vegetables. In this study, potatoes were tested as boiled [with peel, without peel, sliced], shallow and deep fried, and cooking under pressure [with peel, without peel, sliced].Onions were tested as boiled [whole and sliced] and microwave [whole and sliced]. Leafy vegetables Leek, leaf of beet, parsley, coriander, common dill and the mixed of them were tested as boiled fried. All tests performed as triplicate and the contents of vitamin C retention were determined by colorimetric method according to the instruction number 5609 of the Institute of Standards and Industrial Research of Iran and were compared to the contents of vitamin C in raw vegetables. The highest decrease of vitamin C was observed in boiled, sliced [without peel] and shallow fried potatoes and onions. In leafy vegetables highest loss of vitamin C was observed from boiled fried. The loss of vitamin C in potatoes and onions by using microwave were small and their vitamin C contents were similar to raw vegetables. The maximum retention of vitamin C in potatoes and onions are obtained by microwave method, with peel and whole, respectively