Comparison of volatile sulphur compound production by cheese-ripening yeasts from methionine and methionine-cysteine mixtures.
Production of volatile sulphur compounds (VSC) was assessed in culture media supplemented with L-methionine or L-methionine/L-cysteine mixtures, using five cheese-ripening yeasts: Debaryomyces hansenii DH47(8), Kluyveromyces lactis KL640, Geotrichum candidum GC77, Yarrowia lipolytica YL200 and Saccharomyces cerevisiae SC45(3). All five yeasts produced VSC with L-methionine or L-methionine/L-cysteine, but different VSC profiles were found. GC77 and YL200 produced dimethyldisulphide and trace levels of dimethyltrisulphide while DH47(8), KL640 and SC45(3) produced mainly methionol and low levels of methional. S-methylthioacetate was produced by all the yeasts but at different concentrations. DH47(8), KL640 and SC45(3) also produced other minor VSC including 3-methylthiopropyl acetate, ethyl-3-methylthiopropanoate, a thiophenone, and an oxathiane. However, VSC production diminished in a strain-dependent behaviour when L-cysteine was supplemented, even at a low concentration (0.2 g l(-1)). This effect was due mainly to a significant decrease in L-methionine consumption in all the yeasts except YL200. Hydrogen sulphide produced by L-cysteine catabolism did not seem to contribute to VSC generation at the acid pH of yeast cultures. The significance of such results in the cheese-ripening context is discussed.
López Del Castillo-Lozano
M
M
UMR782 GMPA, AgroParisTech INRA, INRA Centre de Biotechnologies Agro-Industrielles, 78850 Thiverval Grignon, France.
Delile
A
A
Spinnler
H E
HE
Bonnarme
P
P
Landaud
S
S
D002611:Cheese / Q000382:microbiology*; D003545:Cysteine / Q000378:metabolism*; D005848:Geotrichum / Q000378:metabolism; D007716:Kluyveromyces / Q000378:metabolism; D008715:Methionine / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013457:Sulfur Compounds / Q000378:metabolism*; D014835:Volatilization; D025062:Yarrowia / Q000378:metabolism; D015003:Yeasts / Q000378:metabolism*
D013457:Sulfur Compounds; D008715:Methionine; D003545:Cysteine