ISOLATION AND PARTIAL CHARACTERIZATION OF THE DIMETHYL SULPHIDE PRECURSOR IN GREEN MALT,AND ITS EFFECT ON BEER DIMETHYL SULPHIDE LEVELS

The component from which dimethyl sulphide (DMS) is produced when green malt worts are heated has been purified and its effects on wort and beer DMS levels studied. The green malt precursor can be split into S-methylmethionine and an as-yet uncharacterized ninhydrin-positive component. When the purified precursor is added to worts derived from kilned malts, it is rapidly taken up by yeast, but there is no resulting increase in DMS production. DMS production during fermentation occurs with worts made from kilned malts but not with worts from green malt; however, this difference is not due to an inhibitor being present in green malt worts. The evidence suggests that malt kilning affects the nature as well as the amount of DMS precursor in malts.