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Functional properties of improved high protein digestibility-hard endosperm sorghum lines
T. TEFERRA (1), D. Amoako (1), J. Awika (1) (1) Texas A&M University, College station, TX, U.S.A..

Sorghum is a drought tolerant crop with known bioactive attributes, but normally underutilized due mainly to reduced endosperm protein functionality. Sorghum proteins cross-link during cooking and restrict starch swelling. On-going work attempts to generally improve sorghum protein functionality for better nutritional and food processing applications. Raw and cooked <i>in vitro</i> protein digestibility of 28 improved sorghum lines, with a combination of high protein digestibility (HD), hard endosperm, and waxy starch traits, were investigated using standard pepsin assay. The sorghum lines were also characterized for water solubility index (WSI) and starch pasting properties (RVA). Generally higher protein digestibility (%) (65.60 - 81.64, uncooked; 55.56 - 65.26, cooked) samples had higher peak (15,888 - 27,654 cP) and final (28,962 - 44,562 cP) viscosities, indicating better starch swelling. Sorghum lines with lower peak (average 10,017 cP) and final (average 14,220 cP) viscosities exhibited lower protein digestibility. The waxy and hetero-waxy lines had lower pasting temperatures and higher WSI. The combined high digestible protein, hard endosperm and waxy/hetero-waxy starch sorghum lines exhibited better functionality than the normal sorghum varieties in terms of protein digestibility and starch pasting properties. These properties are important for improved sorghum nutritional quality for populations in the major producing areas (Africa and Asia), and processing functionality as ingredients in commercial foods.