RESUMEN
Monogastric animals exhibit different biological responses to structurally diverse glucosinolates and their transformation products, depending on the dietary levels. The transformations of 2-hydroxyalkenyl and aromatic glucosinolates were examined in vitro under gastric conditions, ex vivo in ligated porcine stomachs and in vivo in a rat model. Intact glucosinolates were almost completely transformed in vitro within 1â¯h at pH 3 (73-88%) and at pH 5 (97-100%) upon addition of Fe2+ ranging from two-fold molar excess. Glucosinolate transformations reached 78-99% when incubated ex vivo in ligated porcine stomachs. Rat in vivo feeding trials showed major reductions (81-84%) in the intact glucosinolate contents upon passage through the gastrointestinal (GI) tract. Non-enzymatic transformations of glucosinolates occur in the stomach, where pH and the level of Fe2+ are primary determinants. This is the first study to show a complex formation between iron-progoitrin and iron-sinalbin, facilitating the transformation into nitriles and thionamides.
Asunto(s)
Glucosinolatos/química , Estómago/química , Animales , Colina/análogos & derivados , Colina/química , Dieta , Compuestos Ferrosos/química , Cromatografía de Gases y Espectrometría de Masas , Concentración de Iones de Hidrógeno , Masculino , Ratas , Ratas Wistar , PorcinosRESUMEN
Combinations of pressure, temperature and time (100-600â¯MPa, 30-60⯰C, 3-10â¯min) influence enzyme activity of the myrosinase-glucosinolate system. Seedlings of Brussels sprouts were used as a model, which constitutes a well-defined and homogenous sample matrix with simple cell structures. A response surface methodology approach was used to determine the combined effect of pressure level, temperature and time on glucosinolate concentration and myrosinase activity in Brussels sprouts seedlings. The effects on residual myrosinase activity and intact glucosinolate concentration differed according to combinations of pressure, time and temperature. The results showed that maximum inactivation of myrosinase and preservation of glucosinolate (85% of the untreated level) was obtained after HP treatment at 600â¯MPa, 60⯰C, 10â¯min. The highest preservation of myrosinase activity compared to untreated seedlings was after HP at 100â¯MPa, 30⯰C, 3â¯min and 10â¯min with low degree of cell permeabilization.