 The study found that the two most common methods of home cooking in China, stir-frying and stir-frying combined with deep frying in soybean oil, resulted in a much greater loss of chlorophyll, soluble protein, soluble sugar and vitamin C. The method which affected these values the least was steaming.Stir frying for five minutes and stir frying combined with boiling caused the highest loss of glucosinolates which according to this study are best preserved by steaming.A study performed by the Spanish National Research Counsel stir fried the broccoli for only 3 minutes 30 seconds and found that nutritional value of these broccoli samples varied depending on which cooking oil was used.