Portal de Periódicos da CAPES

Distribution of S -Alk(en)ylcysteine Sulfoxides in Some Allium Species. Identification of a New Flavor Precursor: S -Ethylcysteine Sulfoxide (Ethiin)

2000; American Chemical Society; Volume: 48; Issue: 2 Linguagem: Inglês

10.1021/jf990938f

1520-5118

Roman Kubec, M. Svobodova, Jan Velı́šek,

Fungal Plant Pathogen Control

The content of S-alk(en)ylcysteine sulfoxides, important nonvolatile flavor precursors, was determined in 15 different Allium species by means of gas chromatography. The method employed is based on derivatization of S-alk(en)ylcysteine sulfoxides with ethyl chloroformate followed by their reduction with sodium iodide. The total content of S-alk(en)ylcysteine sulfoxides varied considerably in the wide range between 0.02 and 1.3% fresh weight. Not only the total content but also relative proportions of individual derivatives varied to a great extent. A novel S-alkylcysteine derivative, S-ethylcysteine sulfoxide (ethiin), not previously reported to occur in Allium species, was found in most of the samples examined in trace amounts. None of the other S-alk(en)ylcysteine sulfoxides, for example, isopropyl, (Z)-1-propenyl, butyl, or pentyl, were detected in any of the samples analyzed, limiting possible levels of each of these components to ≤1 ppm in fresh weight. Keywords: S-alk(en)ylcysteine sulfoxides; alliin; methiin; propiin; ethiin; isoalliin; flavor precursor; Allium; ethyl chloroformate