Department of Food Science and Human Nutrition, University of Illinois , Urbana, Illinois 61801, United States.
J Agric Food Chem. 2012 Jul 11;60(27):6743-8. doi: 10.1021/jf2050284. Epub 2012 May 15.
In broccoli, sulforaphane forms when the glucosinolate glucoraphanin is hydrolyzed by the endogenous plant thiohydrolase myrosinase. A myrosinase cofactor directs hydrolysis away from the formation of bioactive sulforaphane and toward an inactive product, sulforaphane nitrile. The cofactor is more heat sensitive than myrosinase, presenting an opportunity to preferentially direct hydrolysis toward sulforaphane formation through regulation of thermal processing. Four broccoli cultivars were microwave heated, boiled, or steamed for various lengths of time. Production of nitrile during hydrolysis of unheated broccoli varied among cultivars from 91 to 52% of hydrolysis products (Pinnacle > Marathon > Patriot > Brigadier). Boiling and microwave heating caused an initial loss of nitrile, with a concomitant increase in sulforaphane, followed by loss of sulforaphane, all within 1 min. In contrast, steaming enhanced sulforaphane yield between 1.0 and 3.0 min in all but Brigadier. These data are proof of concept that steaming for 1.0-3.0 min provides less nitrile and more sulforaphane yield from a broccoli meal.
在西兰花中，当内源性植物硫代葡萄糖苷酶黑芥子酶水解葡糖异硫氰酸盐前体物葡萄糖硫苷时，会形成萝卜硫素。黑芥子酶辅助因子会促使水解反应偏离生物活性萝卜硫素的形成，转而生成无活性的产物——萝卜硫素腈。该辅助因子比黑芥子酶更不耐热，为通过调节热加工来优先促使水解反应生成萝卜硫素提供了可能。将 4 个西兰花品种分别进行微波加热、煮沸或蒸汽处理，处理时间各不相同。未加热西兰花水解过程中生成的腈占水解产物的比例在品种间存在差异，范围为 91%至 52%（Pinnacle＞Marathon＞Patriot＞Brigadier）。煮沸和微波加热会导致腈的初始损失，同时萝卜硫素的含量增加，随后萝卜硫素也会损失，所有这些变化都在 1 分钟内发生。相比之下，蒸汽处理除了在 Brigadier 品种中，均能在 1.0-3.0 分钟内提高萝卜硫素的产量。这些数据证明了 1.0-3.0 分钟的蒸汽处理可以降低西兰花餐中腈的含量，并提高萝卜硫素的产量。
