Effect of germination duration on nutritional and functional properties of sorghum (Sorghum bicolor): The case of Girana and Miskr varieties

Abstract

The effect of germination duration on proximate, minerals, anti-nutritional factors and functional properties of two local sorghum varieties (Girana and Miskr) were investigated. A 2*3*2 full factorial design was used to conduct the experiment. Sorghum varieties were soaked for 24 hours at room temperature and germinated for 24, 48 and 72 hours in duplicate. The germinated and control sorghum grains were milled. The analysis and measurement of dependent variables were done in triplicate. The collected data were subjected to analysis of variance using SPSS statistical software. On average after 72 hours germination 9.68% and 9.52% reduction in pH and 34.5% & 16.6% increase in TTA was observed which may improve product stability and mineral absorption. Similarly crude protein content showed a significant (p<0.05) increase from 10.35±0.04% to 12.59±0.15% and 10.17± 0.02 to 12.75±0.136% for Girana and Misker varieties, respectively. A significant (p< 0.05) decrease in crude fat and carbohydrate content was observed for both varieties that in turn brought about a decrease in the average energy value of nearly 8kcal/100gm of sorghum flour. Germination resulted in a significant (p< 0.05) average 50% and 53 % reduction in phytate and tannin content of Girana and Misker varieties respectively. Germination shows a significant (p < 0.05) increase of iron from 7.15±0.03 to 7.51±0.23 and from 7.42±0.1 to 7.85±0.17 at 48 hours for Girana and Misker varieties respectively. Moreover, phytate/zinc molar ratio significantly decreased well below 15 for both varieties. Improvement in functional properties of sorghum as measured by WAI, WSI and viscosity was also observed after 72 hours germination.

Key words: Anti-nutritional factor, bioavailablity, functional properties, mineral composition, proximate, and sorghum