LOW PROTEIN DIGESTIBILITY OF COOKED SORGHUM – CAUSES AND NEEDS FOR FURTHER RESEARCH

Sorghum (Sorghum bicolor (L.) Moench) is cultivated by farmers on a subsistence level in the semi-arid tropics worldwide and consumed as a food staple by humans. Sorghum proteins have poor digestibility when wet cooked and this constitutes a nutritional limitation to its use as food. The factors affecting wet cooked sorghum protein digestibility may be categorised into exogenous factors (grain organisational structure, polyphenols, phytic acid, starch and non-starch polysaccharides) and endogenous factors (disulphide and non-disulphide crosslinking, kafirin hydrophobicity and changes in protein secondary structure). Depending on the nature or state of the sorghum grain, namely whole grain, endosperm, protein bodies, high tannin or condensed-tannin-free, more than one factor may be important at any time. Protein crosslinking may be the greatest factor that influences sorghum protein digestibility