Alkaline Pretreatment and Fermentation Modifies Protein Fractions and Tannins Content of Karamaka -A High-Tannin Sorghum Cultivar

Aims: To study the effect of soaking in 0.20% NaOH for 8 h, followed by fermentation for 16 h on tannins content and protein fractions.

Study Design: Factorial Experimental design.

Place and Duration of Study: Department of Food Science and Technology, Faculty of Agriculture, University of Khartoum, Sudan and Food Research Center, Shambat, Sudan, between July 2007 and May 2008

Methodology: A high-tannin sorghum (Sorghum bicolor L. Moench) cultivar (Karamaka) was soaked in 0.20% NaOH for 8 h followed by fermentation for 16 h. The effect of soaking and fermentation was studied on tannins content and protein fractions, and untreated sorghum was used as a control.

Results: Results showed that soaking the sorghum grains in NaOH for 8 h caused a decrease in tannins content by 41.96%. Combining soaking and fermentation further lowered the tannins content of sorghum by 59.09%, with a maximum reduction of 81.44%. Soaking in NaOH and fermentation caused a significant (P≤0.05) increase in the albumins fraction by 40.97%, accompanied by a significant reduction in the glutelins fraction by 46.44%.

Conclusion: This modification of sorghum protein fractions along with the decrease in the tannins content can indicate improvement in the quality of sorghum proteins and therefore improve the nutrition status of populations where sorghum is staple food.