Peer review

The nutritional quality of whole and decorticated sorghum grains (Tetron, Dabar, Feterita) from Sudan, and various dishes prepared from sorghum, was determined in rat balance tests. From these tests it is concluded that sorghum is low in lysine, and, therefore, has a low biological value. On the other hand, the true digestibility of protein, as well as digestible energy, is very high with values above 90%. True digestibility of the protein decreased when a porridge (ugali) was cooked from the variety Dabar (low polyphenol) but there was an increase in biological value compared with the raw grain. These changes were eliminated if the pH was adjusted to 3·9 before cooking. These effects of cooking were much more pronounced for the variety Feterita (high polyphenol). In pancakes (Kisra) fermented at pH 3·9, there were only minor effects on the nutritional quality due to cooking for all sorghum varieties studied. Cooked, fermented and cooked, unfermented, acid-adjusted Aceda (a thin fermented gruel) had slightly lower digestible energies and lower true protein digestibilities, but higher biological values, than uncooked, fermented Aceda, snowing that the protective effect of acidification observed with Ugali did not occur with Aceda. Marissa, a sorghum beer, had a higher biological value after sieving than did the unsieved brew but true protein digestibility was negatively affected by Marissa preparation.

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