Biochemical changes occurring during traditional Sudanese processing of Kisra bread

Author: Magdi A. Osman ^1*, Ibrahim E. Abdel Rahman ¹, Siddig H. Hamad ¹ and Hamid A. Dirar ²

Received 12 August 2009, accepted 12 April 2010.

Abstract

Changes in crude protein, soluble sugars and organic acids, during traditional Kisra bread preparation from of three sorghum varieties were investigated. Fermented dough was prepared in the traditional way used by Sudanese housewives. For the three varieties the protein content was not significantly increased during the fermentation. Traditional fermentation caused decrease in soluble sugars content, whereas the main by-products of the fermentation, lactic acid, acetic acid and ethanol increased. The pattern of change in the level of soluble sugars of the three sorghum varieties were similar. During the first 4 h of fermentation, glucose concentration increased by 259.0%, 102.0% and 73.0% for Fetarita, Safra and Ahmer variety, respectively. Thereafter it started to decrease at a steady rate towards the end of the fermentation process. The fructose concentration was decreased and completely utilized after 12, 16 and 20 hours for Safra, Ahmer and Fetarita varieties respectively. Sucrose in three varieties was completely utilized after 4 hours, while maltose was completely utilized after 8 h. Lactic acid production started from the beginning of fermentation to the end, while production of acetic acid and ethanol started after 4 hours of fermentation and continued to increase at slow rate. Fetarita variety had the least amount of lactic acid, acetic acid and ethanol, while there was no variation between Safra and Ahmer variety.

Key words: Sorghum, fermentation, glucose, maltose, sucrose, lactic and acetic acids, ethanol.