| Abstract: | ![]()
In pilot brewing trials where wort boil time was varied from 15 min up to 2 hours the DMS contents 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 0.02 min?1, implying a half life of about 35 min. The breakdown 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 0.18 min?1 (t1/2 ～ 4 min) when the evaporation rate was 17%/h. |
