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Gas-chromatographic determination of S-methylcysteine sulfoxide in cruciferous vegetables

Kubec, Roman, Svobodová, Markéta, Velíšek, Jan
European food research & technology 2001 v.213 no.4-5 pp. 386-388
Armoracia rusticana, Brassica, Eutrema, Lepidium sativum, Raphanus, Wasabia japonica, gas chromatography, horseradish, iodides, s-methylcysteine sulfoxide, sodium, vegetables
The content of S-methylcysteine sulfoxide, also known as methiin, was determined in 12 common cruciferous species (members of the Brassica, Raphanus, Eutrema, Armoracia, and Lepidium genera) by means of gas chromatography (GC). The method employed is based on derivatization of S-methylcysteine sulfoxide with ethyl chloroformate followed by reduction of the derivative with sodium iodide. In the former two genera, methiin was present in the range of 0.06–3.18 g kg–¹of fresh weight. On the other hand, only traces of methiin were found in wasabi (Eutrema wasabi Maxim) and none was detected in horseradish (Armoracia rusticana G M et Sch) or garden cress (Lepidium sativum L), limiting its possible content in these two species to ≤0.001 g kg–¹of fresh weight. Traces of an S-ethylcysteine derivative, likely S-ethylcysteine sulfoxide, also known as ethiin, were found in garden cress. The advantages and drawbacks of the GC determination over other commonly used methods are discussed.