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MBAA TQ http://dx.doi.org/10.1094/TQ-52-4-1018-01  |  VIEW ARTICLE
Processability of Laboratory-Malted Nigerian-Grown Red and Yellow Sorghum Varieties at Different Mashing Temperatures and Effect of Exogenous Enzymes on Extract Recovery

B. N. Okolo (1), A. N. Moneke (1), F. J. C. Odibo (1), O. C. Amadi (1), T. N. Nwagu (1), and R. C. Agu (1,2). 1. Department of Microbiology, University of Nigeria. 2. The Scotch Whisky Research Institute, Research Avenue North, Riccarton, Edinburgh, EH14 4AP, Scotland.

The processability of laboratory-malted Nigerian-grown red and yellow sorghum cultivars was studied at 65 and 85C. The infusion mashing at 65C gave poor extract yields for both sorghum malts when done without enzyme addition. Under this mashing condition, red sorghum malt produced twice the extract yield observed for yellow sorghum malt. Higher extract yield was obtained from both sorghum malts when infusion mashing was carried out at 85C without enzyme addition. In general, added commercial enzyme preparations improved extract yield obtained from the malts of both sorghum varieties at both infusion temperatures studied. Surprisingly (due to high gelatinization temperature of sorghum), infusion mashing at 65C rather than 85C gave higher extract yield when mashing was performed with individual commercial enzyme preparations. Key result highlights showed that addition of α-amylase produced similar effects on both red and yellow sorghum malts, increasing extract yield from both sorghum malts by 67%. Addition of β-glucanase was more effective in producing higher extract yield in red sorghum malt, whereas added protease produced higher extract yield in yellow sorghum malt than in the red sorghum variety. Supplementing sorghum malts with commercial α-amylase produced the best results for both sorghum malts at 65C mashing. Our study showed that the use of a single commercial enzyme preparation (α-amylase) significantly improved extract yield obtained from sorghum malt when mashing was carried out at 65C. Processing (mashing) sorghum malt at 65C will reduce the cost of production in terms of cost of enzyme and energy requirement.