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Influence of Different Cooking Methods on the Concentration of Glucosinolates and Vitamin C in Broccoli

Ana Soares, Conrado Carrascosa, António Raposo
Food and bioprocess technology 2017 v.10 no.8 pp. 1387-1411
Brassica, antioxidant activity, ascorbic acid, boiling, broccoli, cell structures, cutting, environmental factors, frying, glucosinolates, mastication, nitriles, oxidative stress, risk, steaming, sulforaphane, thiocyanates, thioglucosidase
Broccoli belongs to the Brassicaceae family and the Brassica genus, also designated crucifers, which has been linked to reduced risk of certain diseases for their content of compounds like glucosinolates (GLS) and vitamin C. Isothiocyanates, nitriles, and thiocyanates are degradation products of glucosinolates, are substances that protect cells against oxidative stress, and present many other health benefits. Vitamin C also contains antioxidant properties that contribute to the beneficial effects that broccoli have for health. The present paper is an overview of the reduction of secondary plant products, such as GLS and vitamin C, by cooking. Nonetheless, these concentrations can be modified if the cell structure of the plant is disrupted, e.g., while cutting, chewing, or cooking. Myrosinase can come into contact with GLS and hydrolyze it to isothiocyanate sulforaphane or sulforaphane nitrile, depending on the environmental conditions, which produces changes in the composition and concentration of GLS. Thus, cooking induces many chemical and physical modifications in food, among which GLS and vitamin C content in broccoli can change. Vitamin C and GLS are water-soluble, which makes them more susceptible to loss during the cooking process. Despite some controversy, most reviewed studies show that conventional cooking methods (boiling, steaming, and frying) and nonconventional ones (microwaving) significantly lead to the degradation of vitamin C and GLS. Nonetheless, steaming is the conventional method that obtains the best result to better preserve these two compounds.