Effect of Fermentation, Malt-Pretreatment and Cooking on Antinutritional Factors and Protein Digestibility of Sorghum Cultivars

Abstract

Two sorghum cultivars namely, Mugud (low tannin) and Karamaka (high tannin) were used in this study. The flour of the seeds of both cultivars was mixed with 5% malt. Then the flour with or without malt was fermented for 16 h. Samples were taken every 2 h during fermentation to study changes in pH, total acidity, crude protein and dry matter. Fermentation of the flour with or without malt resulted in an increase in crude protein content and total acidity for both cultivars. Moreover, the fermented flour with or without malt was cooked to study changes in phytate, tannins and in vitro protein digestibility of the cultivars. A highly significant (P < 0.05) reduction in antinutritional factors (phytate and tannins) was observed for malted and fermented flour compared to the fermented dough. Cooking significantly (P < 0.05) reduced the in vitro protein digestibility of the treated cultivars but the extent of the reduction is lower in malted samples. Fermentation alleviates the adverse effect of cooking on sorghum protein digestibility after addition of malt. Results obtained revealed that addition of malt followed by fermentation is a useful method to improve the nutritional value of sorghum even after cooking.