Submitted to: Brewers Digest
Publication Type: Trade Journal
Publication Acceptance Date: 3/26/2007
Publication Date: 6/15/2007
Citation: Duke, S.H., Henson, C.A. 2007. Osmolyte Concentration in Green and Kilned Malt as Indicators of Malt Quality. Brewers Digest. June, 2007.
Technical Abstract: This research was conducted to test the hypothesis that osmolyte concentrations of green and/or kilned malts can be used as early indicators of finished malt quality. Barley seeds were steeped and germinated in a mircomalter for six days during which time samples were collected every 24 h. Green malt samples were analyzed for malt osmolyte concentration (GMOC) and were kilned and analyzed for osmolyte concentration (OC), malt extract (ME), diastatic power (DP), alpha-amylase activity, soluble/total protein (S/T), and beta-glucan concentration. GMOC and OC increased most rapidly between days 1 - 3 or 1 - 4 of germination, respectively, and plateaued or declined thereafter. ME typically followed the same pattern as GMOC and OC although the rates of increase in ME slowed and/or plateaued sooner than did GMOC and OC values. This suggests that GMOC and OC continue to measure storage compound degradation longer than does ME. ME and OC were correlated on days 2-4 and day 6 (r=0.740 – 0.942, P<0.0001). Days 2 and 3 OC values correlated with ME values from all days (r=0.740 – 0.0.942, P<0.0001). ME and GMOC were correlated on all days of germination (r=0.878 to 0.943, P<0.0001). GMOC from day 1 were correlated with ME from days 1 – 5 (r=0.756 – 0.886, P=0.0003 to <0.0001) and GMOC from day 2 were correlated with ME from days 1-6 (r=0.769 – 0.910, P=0.0002 to <0.0001). OC from day 2 correlated with beta-glucan concentrations from days 2 – 6 (r=-0.702 to -0.830, P<0.0001). GMOC and beta-glucan concentrations were correlated on days 1 – 6 (r=0.788 to -0.896, P<0.0001). No significant correlations were found between OC and DP or alpha-amylase on any day. GMOC were correlated with alpha-amylase and S/T for days 3 – 6 (r = 0.733 to 0.890, P=0.002 to <0.001). Collectively, these data suggest that both OC and GMOC values from early periods of germination can be used as indicators of finished ME and of selected other malt quality values from malts produced 1 – 4 days later.