Cysteine Sulfoxides and Alliinase Activity of Some Allium Species

The flavor precursors of 17 species belonging to the Alliaceae family were analyzed by HPLC, and results were evaluated with respect to the classification of species into their genus, subgenus, and section. Identification and quantification of these precursors were carried out by synthetic and natural reference materials. In addition, nine of these species were investigated in terms of their alliinase activity. Alliinase (EC 4.4.1.4) catalyzes the conversion of odorless (+)-S-alk(en)yl-l-cysteine sulfoxides into volatile thiosulfinates. Cysteine sulfoxides as well as alliinase activity were found in all investigated samples, and (+)-S-methyl-l-cysteine sulfoxide was most abundant. (+)-S-Propyl-l-cysteine sulfoxide was detected in only a few, not closely related, species. Analysis of the crude protein extract of nine species gave evidence that alliinase activities of samples were similar in terms of pH and temperature optimum, KM value, and substrate specificity. For all investigated protein extracts, the ...