DIMETHYL SULFIDE (DMS)
The perceived flavor intensity can be expressed as follows where P is the perceived flavor intensity, C is a concentration of DMS in beer, and T is the taste threshold in beer:2
P = (beer style constant) = ( C/T ) n
The level of DMS in unmalted barley, wheat, rye and corn syrup is negligible.
The amount of DMS in corn grits has been reported to be approximately 0.4 ppb.1
Some typical levels of DMS and SMM in different varieties of malt are shown in Table IV.4
TABLE III DMS and SMM LEVELS in TYPICAL MALTED BARLEY KERNEL MALT KERNEL DMS (ppb) SMM (ppb) 1) Husk 0.81 0.67 2) Starchy Endosperm 1.5 1.2 3) Embryo and Scutellum 5.9 2.2 4) Crospire 15.0 14.0
- (Biosynthesis activity 2-4)
TABLE IV REPORTED DMS and SMM LEVELS in DIFFERENT MALT VARIETIES MALT KERNEL DMS (ppb) SMM (ppb) SMM (ppb)
- Larken 12.9 12.0 24.9
- Proctor, Pale Ale 7.1 3.7 10.8
- Klages (2 row) 9.2 2.0 11.2
- U.S. Malt: (high modification, low kilning temperature)
- British Malt: (moderate modification, higher kilning temperature)
An American maltster reported that typical combined DMS/SMM levels in North American brewers malt averaged 10-15 ppb. But during years of high protein levels, for example the '88 drought, levels may approach 20 ppb.
TABLE V SMM LEVELS in MALT vs. DMS in FINISHED LAGER BEER MALT BEER % INCREASE
SMM (ppb) DMS (ppb) (SMM to DMS) 3.2 38.0 1090 4.6 61.0 1200 6.0 78.0 1200 8.4 98.0 1070
TABLE VI REACTIONS CONTRIBUTING TO DMS FORMATION
(CH3)2S-CH2-CH2-CH(NH2)-COOH(CH3)2 + OH >(CH3)2S<(oxidation/reduction)>(CH3)2S=O S-Methyl methionine Dimethyl sulfide Dimethyl Sulfoxide SMM DMS DMSO
Infromation from http://www.abtonline.com
