SYNTHESIS OF DIMETHYL SULPHIDE DURING FERMENTATION BY A ROUTE NOT INVOLVING THE HEAT-LABILE DMS PRECURSOR OF MALT

Pilot scale brewing studies showed that dimethyl sulphide (DMS) can be produced during fermentation substantially in excess of that predicted by measurement of the DMS potential of the wort. This occurred in low temperature fermentations conducted in conical vessels but not if open vessels were used. Neither the type of malt used nor the length of the wort boil substantially influenced the extent of this excess DMS production although they may have affected liberation from the yeast of unidentified material which released DMS on treatment with hot alkali. It is suggested that yeast can synthesise S-methyl-L-methionine (SMM) and that metabolic breakdown of this compound was responsible for some of the DMS produced.