Dimethyl sulphide is a normal flavour component of many lagers, particularly Continental lagers, but is not present in ales in sufficient quantity to affect flavour. The kilning stage of malting determines the extent to which a precursor capable of being converted to dimethyl sulphide by yeast will be present in wort. Worts pre pared from Continental malts appear to contain more of this precursor than worts from British malts and the derived beers thus contain more dimethyl sulphide. Amounts of dimethyl sulphide formed from the precursor during fermentation depend on the strain of yeast employed, whilst the amounts retained in solution depend on physical factors such as temperature and rate of evolution of carbon dioxide.

Laboratory investigations of the quality of worts produced from green malt, from mixed grists of green malt and unmalted cereals, and by the action of commercial enzymes on barley starch are described. Green malt alone gives sweet worts which are very highly fermentable and contain much nitrogenous material but are of very reduced anthocyanogen content. Satisfactory yields of extract are obtained in the conversion of unmalted cereals by green malt if they are finely ground. Additional treatment such as presoaking or gelatinization usually further increases the extract and is essential where certain enzyme preparations are employed.

Additional evidence is presented that isohumulone A contains two components and that there are six isohumulones in beer. The significance of methods for the estimation of bitterness in beer is discussed; certain rapid methods give good correlation with bitterness and are excellent for quality control, though anomalies may occur. The beer components which originate in the various hop resins are assessed and in this connection the bittering ability of aged hops is shown not to be due to humulinone.

Beers brewed from grists containing between 3% and 30% of crystal malt have been examined in order to identify the volatile substances contributing to the characteristic flavour. Several oxygen, nitrogen and sulphur heterocyclic compounds together with certain fusel oil components are present at higher levels in beers brewed with crystal malt. Some of these compounds have also been isolated from the malt itself and from heat-treated model systems.The results are consistent with these compounds being derived from sugars and amino-acids via Amadori rearrangement products.

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