Characterization of Tannin and Study of in vitro Protein Digestibility and Mineral Profile of Sudanese and Indian Sorghum Cultivars

Abstract

The study was conducted to investigate chemical composition, mineral profile, tannin content, and effect of cooking on in vitro protein digestibility , and separation and identification of free and bound phenolic acids of Sudanese sorghum cultivar (namely feterita) and Indian sorghum cultivar (namely CSH5). Chemical composition of the two sorghum cultivars was determined. Sudanese cultivar showed significantly (p<0.05) high moisture, ash, protein, and fat while Indian cultivar was significantly higher (P<0.05) in fiber and carbohydrate contents. Cupper, calcium, iron, phosphorus, potassium, and sodium were determined for the two cultivars. Results revealed that, Sudanese cultivar was significantly higher (P<0.05) in cupper, calcium, iron, and sodium while Indian cultivar was significantly higher (P<0.05) in phosphorus and potassium content. Tannin content in Sudanese cultivar was significantly (P<0.05) higher compared to Indian cultivar. Effect of cooking on in vitro protein digestibility revealed that cooking significantly (P<0.05) reduced the in vitro protein digestibility of the two sorghum cultivars. The phenolic acids (PAs) as free and bound form content were separated and identified using high performance liquid chromatography (HPLC) for the two sorghum cultivars. Syringic, p-coummaric, ferulic acid were detected as free form of phenolic acids of Indian cultivar while gallic , protocatechuic, gentisic, caffeic, p-coummaric , and ferulic acids were detected in free form of Sudanese cultivar. Gallic, protocatechuic , gentisic, and p-coummaric were not detected in free form in Indian cultivar while syringic acid was not detected in Sudanese cultivar in free form. Indian cultivar contained high caffeic and ferulic acid in free form compared to Sudanese cultivar. Syringic, caffeic, p- coummaric and ferulic acids were detected in bound form in Indian cultivar while gallic, protocatechuic, caffeic, p-coummaric and ferulic acid were detected in bound form in Sudanese cultivar. Gallic, protocatechuic and gentisic acids were not detected in free and bound form in Indian cultivar while p-coummaric acid was only detected in bound form in Indian cultivar. Syringic, caffeic, p-coummaric and ferulic acids content in bound form were high in Indian cultivar than Sudanese cultivar. Generally phenolic acids of the two cultivars exist mostly in bound form.