Effect of Floor Germination Temperature on Dimethyl Sulphide Precursors Present in Malt and Sensory Characteristics of Beer
MetadataShow full item record
Dimethyl sulphide in beer tends to predominate overall flavour perceptions at very low threshold values. During malting, germination temperatures of steeped barley above 20oC induce formation of DMS precursors in malt (4), which ultimately evolve to DMS during brewing. To compare the impact of floor and pneumatic germination temperatures on the development of DMSP, two-row CDC Copeland barley was floor and pneumatically malted. Additionally, through a laboratory-scale floor malting protocol, barley was germinated at 10.0, 17.5 and 25.0oC to obtain green and kilned malt and fermented wort. Lastly, 30 L pilot brews were executed with floor and pneumatic malt to evaluate DMS threshold in beer made from floor malt. It was established that floor and pneumatic malting had a significantly different (p-value < 0.05) impact on DMSP levels generated. GC analysis detected the highest DMSP levels of 41.0 + 10.3 μg/g and 10.8 + 2.8 μg/g in pneumatic and floor malt, respectively. GC analysis of green malts germinated at 10.0, 17.5 and 25.0oC revealed no significant difference (p-value > 0.05) between DMSP levels generated at any germination temperature. Following kilning of these green malt samples at 63.0oC for 24.0 hours, GC results displayed no significant difference (p-value > 0.05) between DMSP levels obtained from samples. Furthermore, No DMSP was detected in fermented wort produced from lab floor malt. Results for sensory analysis for DMS (take-off threshold) in “floor malt” beers were inconclusive. Therefore, it was suggested that floor malt germination temperature can result in production of suitable malt which is suitable for brewers to use without resulting in off flavour development in final beer.