Nutritional Quality of Fermented Sorghum-Soybean Composite Flour

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Asma Abu Baker Abu Baker Tahir, Tahir
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ABSTRACT Nutritional Quality of Fermented Sorghum-Soybean Composite Flour Ph.D Asma Abu Bakr Abu Bakr The nutritional quality of sorghum (Sorghum bicolor L.) Tabat cultivar is poor like other cereals, so the main objective of this study was to fortify this cereal protein by use of soybean flour. Tabat cultivar was obtained from Khartoum local market, and soybean flour (Glycin max L. Merrill) from U.S.A super market. Sorghum was supplemented with soybean flour to give a total protein content of about 20%. Sorghum flour and sorghum-soybean composite flour were fermented in the presence of starter at 37 C for 16hours and the samples were taken at 2hours intervals. The pH, crude protein, in vitro protein digestibility, protein fractions and amino acids of fermented and supplemented sorghum were determined. The pH of all samples decreased during fermentation. The protein content significantly (PX04;0.05) increased for 14hours dough for uncooked fermented sorghum dough. Supplementation and fermentation improved the in vitro protein digestibility of sorghum dough, which was reduced significantly after cooking. The globulin and albumin fractions of fermented samples significantly (PX04;0.05) increased during fermentation period and decreased significantly (PX04;0.05) as a result of cooking. The results revealed that G3-glutelin was the major fraction of sorghum dough, it reached its maximum value after 2hours of fermentation. Effect of supplementation by soybean flour on G3-glutelin revealed that, it fluctuated during fermentation and reaching the maximum value 4hours after fermentation. After cooking, globulin, albumin and prolamine fractions of supplemented samples decreased, while G1-glutelin, G2-glutelin and insoluble protein increased. The amino acids content fluctuated during fermentation and a significant difference (PX04;0.05) was found between the fermentation periods. Lysine is the second limiting amino acid (1.1g/100g protein), representing only 19.5% compared with the FAO reference pattern. However, it was improved to 2.0g/100g protein on supplementation with soybean flour. All essential amino acids decreased after cooking for all fermentation periods when compared with the uncooked dough. English Abstract
Nutritional Quality of Fermented Sorghum-Soybean Composite Flour