title: Development and validation of a plate technique for screening of microorganisms that produce volatile sulfur compounds.
abstract: Volatile sulfur compounds (VSCs) are of major importance for flavor development in foodstuffs such as cheeses. Such compounds originate from the amino acid l-methionine, which can be degraded to methanethiol (MTL), a common precursor to a variety of other VSCs. A plate assay based on double-layer petri dishes containing 5,5'-dithio-bis-2-nitrobenzoic acid (DTNB), a chemical used for the estimation of free thiols, in the upper layer provides an easy and reliable detection method for thiol-producing, cheese-ripening microorganisms. MTL production was quantitated by measuring the yellow-orange color intensity resulting from reaction with DTNB. Using this method, 18 Geotrichum candidum strains isolated from cheeses were compared, and the color intensity was found to be correlated with the production of microbial VSCs as measured by gas chromatographic analysis.
authors.affiliation: ADRIA Normandie, Boulevard du 13 juin 1944, BP2, F-14310 Villers Bocage, France.
authors.forename: Hugues
authors.initials: H
authors.lastname: Guichard
authors.forename: Pascal
authors.initials: P
authors.lastname: Bonnarme
mesh_terms: D002611:Cheese / Q000382:microbiology*; D004136:Dinitrobenzenes / Q000737:chemistry / Q000378:metabolism; D005848:Geotrichum / Q000302:isolation & purification* / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D008828:Microbiological Techniques; D013438:Sulfhydryl Compounds / Q000032:analysis* / Q000378:metabolism; D014835:Volatilization
chemical_list: D004136:Dinitrobenzenes; D013438:Sulfhydryl Compounds; C005231:methylmercaptan; D008715:Methionine; C010936:2,4-dinitrothiocyanatobenzene