The effect of germination time on malt quality of six sorghum (Sorghum bicolor) varieties grown at Melkassa, Ethiopia

Abstract

The effect of germination time (48, 96 and 144 h) on malt quality of six sorghum varieties was investigated to determine the potential of grain sorghum cultivars in the local brewery industry. Six sorghum varieties (Gambella 1107, Macia, Meko, Red-Swazi, Teshale and 76 T1#23) were evaluated in a randomized complete block design with three replications. The results showed that both germination time and variety had a significant effect (p ≤ 0.05) on sorghum malt quality. The hectolitre weight (kg hL−1 at 12.5% moisture), germination energy (%), crude protein (%) and flour starch amylose content (%) were: 75.8–82.9, 96–99, 7.0 − 11.9 and 16.0 − 23.0, respectively. The sorghum malt diastatic power (DP, °L), free amino nitrogen (FAN, mg L−1), hot water extract (HWE, %) and malting loss (%) were: 18.96 − 31.39, 185.67 − 343.29, 41.85 − 85.08 and 8.68 − 27.56, respectively. Malting loss, HWE and FAN increased with germination time. The DP increased as the germination duration increased from 48 to 96 h, but the difference between 96 and 144 h was not significant. Considering the excessive malting loss and marginal increase in HWE beyond 96 h, this study suggests that the optimum malting duration would be around 96 h. Among the varieties tested, Teshale and Gambella 1107 produced the better malt quality. Copyright © 2012 The Institute of Brewing & Distilling