Evaluation and Characterization of Selected Varieties of Sorghum for Malting Purpose in Ethiopia

Abstract

Background Sorghum is staple cereal crop in Ethiopia which is used as a food source and traditional beverage. Seven sorghum varieties were used, planted malted, and extracted under similar conditions to assess their quality for brewing. The experiment was performed and analyzed their physicochemical, malting, biochemical and wort quality parameters investigated employing standard procedures. The grain quality parameters for seven sorghum varieties such as ash, moisture, protein, tannin, starch, amylose, iron and zinc, malting, and wort quality parameters were analyzed. Data were analyzed utilizing ANOVA [at 95% significant level] and correlations using SPSS 14 software. Result Results showed the two cultivars ESH-1 an ESH-4 had a protein percentage greater than 12%. While the highest starch value was recorded in Melkam (65.39 %) variety. Debra grain recording the highest zinc (38.86 ppm) content and ESH-4 was recorded the highest iron (38.66 ppm) content. All the cultivars had good germinative capacities more than 80% and more than 90% were recorded at 24 and 48 hours respectively. The varieties Debere and Melkam have recorded the highest germinative energy values of 88 and 67 % at 12 hours respectively and while 100% of germination energy values were recorded at 24 hours. Varieties with high friability were Debere and Melkam which indicates high lautering performance. Varieties with low friability were Argity and ESH-4 indicated that under modification can lead to poor mash conversion and more high viscosity. The cross correlations between amylose, starch and protein were showed the significant difference at p<0.05. The correlations between the amylose pairs of amylose-starch (0.686) and amylose-protein (0.685) were found to be high and positive. Yield was negatively significantly correlated to amylose, starch, protein, ash and moisture content (r = -0.705, -0.590, -0.441, -0.201 and -0.0.178) respectively. However, most of the cultivars fulfilled the quality requirements and within the acceptable range of the European Brewery Convention (EBC) and Asela Malt factory standard (Ethiopia). Conclusion This study showed that the cultivars have good potentials for use as malting materials in beverage making. Some of the sorghum varieties have been identified to be useful as nutritious source of food and for use in the malting industry.