生物谷報道：來自Warwick大學(xué)的科學(xué)家最近發(fā)現(xiàn)，傳統(tǒng)的將蔬菜完全煮沸的英式烹飪方法將破壞蕓苔類蔬菜——例如花椰菜,、甘藍(lán),、綠卷心菜等中的抗癌成分。
之前的研究顯示,，食用蕓苔類蔬菜將降低腫瘤風(fēng)險,。這是由于蕓苔類蔬菜中含有一種稱為硫代葡萄糖苷的物質(zhì)，它將會經(jīng)由代謝產(chǎn)生一種抗癌物質(zhì)硫氰酸鹽,。但是在這之前,，科學(xué)家并不清楚硫代葡萄糖苷和硫氰酸鹽是否受到蔬菜儲存以及烹飪的影響。
來自Warwick醫(yī)學(xué)院的Paul Thornalley教授以及化學(xué)系Lijiang Song博士從當(dāng)?shù)厣痰曛匈徺I了多種蕓苔類蔬菜,，然后在30分鐘內(nèi)運送到實驗室,。然后他們用不同方法烹飪，包括煮沸,、蒸熱,、微波爐和煸炒等，來研究這些方法對其中相關(guān)物質(zhì)的作用,。
結(jié)果表明,。煮沸對于蔬菜中的硫代葡萄糖苷的破壞最為嚴(yán)重。在煮沸30分鐘后,，硫代葡萄糖苷的損失為：椰菜77%,，甘藍(lán)58%，花椰菜75%,，綠卷心菜65%,。
其它烹飪方式分別為：蒸0-20分鐘、微波爐加熱0-3分鐘,、煸炒0-5分鐘,。這些方法都不會造成硫代葡萄糖苷的顯著損失。而且在家中的室溫下或是冰箱中儲存也只會造成這類物質(zhì)的少量流失,。
但是在85度情況下會導(dǎo)致硫代葡萄糖苷損失達(dá)到33%,。這是由于其中的蔬菜物質(zhì)破碎融化造成的?？茖W(xué)家還發(fā)現(xiàn),，對于蕓苔類蔬菜的一般烹飪前準(zhǔn)備不會造成物質(zhì)損失，但是如果是將它們切的很碎,，則在切碎后的6小時損失量將達(dá)到75%,。
英文原文：
http://www.physorg.com
Research says boiling broccoli ruins its anti-cancer properties
Researchers at the University of Warwick have found that the standard British cooking habit of boiling vegetables severely damages the anticancer properties of many Brassica vegetables such as broccoli, Brussel sprouts, cauliflower and green cabbage.
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Past studies have shown that consumption of Brassica vegetables decreases the risk of cancer. This is because of the high concentration in Brassicas of substances known as glucosinolates which are metabolized to cancer preventive substances known as isothiocyanates. However before this research it was not known how the glucosinolates and isothiocyanates were influenced by storage and cooking of Brassica vegetables.
The researchers, Prof Paul Thornalley from Warwick Medical School at the University of Warwick and Dr Lijiang Song from the University of Warwick’s Department of Chemistry bought Brassica vegetables, (broccoli, Brussel sprouts, cauliflower and green cabbage) from a local store and transported them to the laboratory within 30 minutes of purchasing. The effect of cooking on the glucosinolate content of vegetables was then studied by investigating the effects of cooking by boiling, steaming, microwave cooking and stir-fry.
Boiling appeared to have a serious impact on the retention of those important glucosinolate within the vegetables. The loss of total glucosinolate content after boiling for 30 minutes was: broccoli 77%, Brussel sprouts 58%, cauliflower 75% and green cabbage 65%.
The effects of other cooking methods were investigated: steaming for 0–20 min, microwave cooking for 0–3 min and stir-fry cooking for 0–5 min. All three methods gave no significant loss of total glucosinolate analyte contents over these cooking periods.
Domestic storage of the vegetables at ambient temperature and in a domestic refrigerator showed no significant difference with only minor loss of glucosinolate levels over 7 days.
However the researchers found that storage of fresh vegetables at much lower temperatures such as 85 °C (much higher than for storage in a refrigerator at 4–8 °C) may cause significant loss of glucosinolates up to 33% by fracture of vegetable material during thawing.
The researchers found that preparation of Brassica vegetables had caused only minor reductions in glucosinolate except when they were shredded finely which showed a marked decline of glucosinolate levels with a loss of up to 75% over 6 hours after shredding.
Source: University of Warwick
