Pilot scale brewing studies showed that dimethyl sulphide (DMS) can be produced during fer mentation 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.

In pilot brewing trials where wort boil time was varied from 15 min up to 2 hours the DMS con tents of the resultant beers were greatly altered without substantial effect on many other aspects of beer quality. The worts were separately fermented by two yeast strains and a consistent difference between DMS levels of the pairs of beers was found which was almost independent of the boil time.The breakdown of the malt-derived DMS precursor in boiling wort was found to be a first order reaction having a rate constant of about 002 min-1, implying a half life of about 35 min. The break down rate of S-methylmethionine in a boiling sucrose solution at pH 5 3 was similar. Free DMS was found to leave this wort substitute rapidly, again as a first order process, but with a rate constant of 018 min-1 (t*~4 min) when the evaporation rate was 17%/h.

SummaryAmyloglucosidase (EC. 3.2.1.3), partially purified from an Aspergillus species, was chemically attached to DEAE cellulose using the bifunctional reagent 2-amino-4,6-dichloro-s-triazine. The action of the insolubilized enzyme derivative on dilute maltose and dextrin solutions was studied in a packed bed. A second and deeper bed was used to demonstrate the possibility of a continuous process for raising the dextrose equivalents of "glucose" liquors of high concentration formed by acid hydrolysis of maize starch.

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