RESUMEN
A blanching step was designed to favor sulforaphane synthesis in broccoli. Blanching was optimised through a central composite design, and the effects of temperature (50-70 °C) and immersion time in water (5-15 min) on the content of total glucosinolates, glucoraphanin, sulforaphane, and myrosinase activity were determined. Results were analysed by ANOVA and the optimal condition was determined through response surface methodology. Temperature between 50 and 60 °C significantly increased sulforaphane content (p<0.05), whilst blanching at 70 and 74 °C diminished significantly this content, compared to fresh broccoli. The optimal blanching conditions given by the statistical model were immersion in water at 57 °C for 13 min; coinciding with the minimum glucosinolates and glucoraphanin content, and with the maximum myrosinase activity. In the optimal conditions, the predicted response of 4.0 µmol sulforaphane/g dry matter was confirmed experimentally. This value represents a 237% increase with respect to the fresh vegetable.
Asunto(s)
Brassica/química , Manipulación de Alimentos/métodos , Glucosinolatos/análisis , Imidoésteres/análisis , Isotiocianatos/análisis , Glicósido Hidrolasas/metabolismo , Calor , Oximas , SulfóxidosRESUMEN
Sulforaphane (1-isothiocyanato-4-(methylsulfinyl)-butane) content in cruciferous vegetables. Sulforaphane is an isothiocyanate which has antimicrobial and anticarcinogenic properties, this compound is found in a wide variety of plants from genus Brassica oleracea, being the most important broccoli and cabbage. The objective of this research was to quantify sulforaphane in the edible parts of broccoli and cabbage leaves by high-performance liquid chromatography (HPLC). Sample preparation for the quantification of sulforaphane include the conversion of glucoraphanin to sulforaphane (45 +/- 2 degrees C for 2.5 h), extracted with dichloromethane, purification of the extract in columns of solid phase extraction and detection by HPLC- UV. Sulforaphane concentration in broccoli is in the range of 214 microg/g DW (stems) to 499 microg/g DW (inflorescences). The purple cabbage (101.99 microg/g DW) has values greater than the green cabbage (7.58 microg/g DW). The inflorescences of broccoli and red cabbage leaves are rich in sulforaphane.