title: Formation of methanethiol and dimethyl disulfide in crushed tissues of broccoli florets and their inhibition by freeze-thawing.
abstract: The formation of methanethiol and dimethyl disulfide in crushed, homogenized, and frozen-thawed tissues of broccoli florets was investigated. These volatile sulfur compounds were produced in crushed florets, but their formation was inhibited in frozen-thawed tissues. Only dimethyl disulfide was formed in homogenized tissues. High pH treatment triggered the release of dimethyl disulfide in frozen-thawed tissues and also enhanced the action of cysteine sulfoxide lyase in all disrupted tissues. Methyl methanethiosulfinate and methyl methanethiosulfonate were not detected in crushed florets; thus, the favored mechanism for the formation of methanethiol and dimethyl disulfide is the chemical disproportionation of methanesulfenic acid. In contrast, the formation of dimethyl disulfide in frozen-thawed and homogenized tissues occurs from the chemical disproportionation of methyl methanethiosulfinate that was detected in these tissues. The inhibition of dimethyl disulfide production during freeze-thawing must be caused by a sudden drop in the pH of the tissue, adherence of dimethyl disulfide on the tissue surfaces, and weakening of the cysteine sulfoxide lyase activity under acidic conditions.
authors.affiliation: Graduate School of Agriculture and Biological Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan.
authors.forename: Artemio Z
authors.initials: AZ
authors.lastname: Tulio
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamanaka
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ueda
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Imahori
mesh_terms: D001937:Brassica / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000032:analysis*; D005511:Food Handling; D005615:Freezing; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D013438:Sulfhydryl Compounds / Q000032:analysis*; D013649:Taste; D014835:Volatilization
chemical_list: D013438:Sulfhydryl Compounds; C005231:methylmercaptan; D004121:Dimethyl Sulfoxide