Thermal and Concentration Impacts on Tannin and Physical Properties Changes during Alkaline Soaking of Sorghum Grain

Tannin is one of the phenolic components present in food ingredients, especially grains and nuts. The tannin content in sorghum grain up to 4.8% depending on the variety. In low concentrations, tannins have benefits if consumed by humans. Meanwhile, at high amounts, tannin acts as an anti-nutritional substance that can inhibit the absorption of protein in digestion. In this study, the process of degrading tannin levels in this study used the soaking method using potassium hydroxide and calcium hydroxide solutions with concentrations (0.05-0.15%) with soaking temperatures of 30, 40, and 50oC. Soaking was carried out for 8 hours with sampling every 1 hour. The use of Calcium hydroxide alkaline solution of 0.15% obtained in the highest dissolved tannin solution in sorghum grain soaking process. The results of soaking process also obtained data on the Water Adsorption Index, Water Solubility Index, and Swelling Power. From this research it is expected to obtain low concentrations tannin of sorghum grain as a quality food ingredient.