Effects of different cooking methods on health-promoting compounds of broccoli

The effects of five domestic cooking methods,including steaming,microwaving,boiling,stir-frying,and stir-frying followed by boiling(stir-frying/boiling),on the nutrients and health-promoting compounds of broccoli were investigated.The results show that all cooking treatments,except steaming,caused significant losses of chlorophyll and vitamin C and significant decreases of total soluble proteins and soluble sugars.Total aliphatic and indole glucosinolates were significantly modified by all cooking treatments but not by steaming.In general,the steaming led to the lowest loss of total glucosinolates,while stir-frying and stir-frying/boiling presented the highest loss.Stir-frying and stir-frying/boiling,the two most popular methods for most homemade dishes in China,cause great losses of chlorophyll,soluble protein,soluble sugar,vitamin C,and glucosinolates,but the steaming method appears the best in retention of the nutrients in cooking broccoli.

Effect of NaCl treatments on glucosinolate metabolism in broccoli sprouts

To understand the regulation mechanism of NaCI on glucosinolate metabolism in broccoli sprouts, the germination rate, fresh weight, contents of glucosinolates and sulforaphane, as well as myrosinase activity of broccoli sprouts germinated under 0, 20, 40, 60, 80, and 100 mmol/L of NaCI were investigated in our experiment. The results showed that glucoerucin, glucobrassicin, and 4-hydroxy glucobrassicin in 7-d-old broccoli sprouts were significantly enhanced and the activity of myrosinase was inhibited by 100 mmol/L of NaCI. However, the total glucosinolate content in 7-d-old broccoli sprouts was markedly decreased although the fresh weight was significantly increased after treatment with NaCI at relatively low concentrations （20, 40, and 60 mmol/L）. NaCI treatment at the concentration of 60 mmol/L for 5 d maintained higher biomass and comparatively higher content of glucosinolates in sprouts of broccoli with decreased myrosinase activity. A relatively high level of NaCI treatment （100 mmol/L） significantly increased the content of sulforaphane in 7-d-old broccoli sprouts compared with the control. These results indicate that broccoli sprouts grown under a suitable concentration of NaCI could be desirable for human nutrition.