Effect of cooking on phytochemicals and VC in vegetables

Objective: To investigate the effect of different domestic cooking methods on anthocyanin, glucosinolates, capsaicin and V C in purple sweet potato, broccoli and green pepper. Methods: Three kinds of vegetable were treated by microwave cooking, steaming, scalding and stir-frying.Then pH differential spectrophotometry was used to determine anthocyanin, HPLC to determine glucosinolates and capsaicin, and 2, 6-dichlorophenol titrimetry to determine V C.Results: Steaming preserved V C was better than Microwave-steaming, scalding was better than stir-frying, and stir-frying was better than microwave- boiling. Steaming preserved anthocyanin was better than Microwave-steaming as well.Stir-frying preserved glucosinolates was better than scalding, and microwave-boiling was the worst.Conversely, microwave- boiling preserved capcaisin was the best, and stir-frying was the worst. Conclusion: When cooking time was controlled shorter, steaming was the best cooking method for phytochemical and vitamins preservation in dark vegetables.