Nutritional Evaluation of Local Bread Types in Iraq

The effect of baking conditions (temperature and time) on the nutritional value of five types of local bread was studied using the Trinitrobenzen sulfonic acid (TNBS) chemical method to estimate the percentage of the amino acid lysine in the bread types studied. It was found that the percentages of lysine in French bread, stone bread, laboratory bread, Arabic loaf, tanoor bread and microwave bread are 2.718%, 2.430%, 2.538%, 2.853%, 2.510% and 3.102% respectively. It was also found that the percentage of lysine in the crust was less than that in the crumb for all types of bread and that the highest percentage of lysine was in the Arabic bread and the lowest in the stone bread. This was not the case for the microwave loaf, however, which had a percentage of 2.939. The nutritional value of the proteins of these types of bread was also studied by the biological method using laboratory rats (White Albino Rats) by estimating the protein efficiency Ratio (PER) , and it was found that the value of (PER) for the types of bread(French bread, stone bread, laboratory bread, Arabic bread, Tanour bread and microwave bread, in addition to the comparison group that was fed casein as a protein source) was (1.419, 1.183, 1.377, 1.708 , 1.254 ,and 1.820 ) respectively. It was 2.939 for the comparison group. These differences were not significant. However, it was found that the Arabic bread was superior in its nutritional value and decreased in stone bread. It was found that there is a linear relationship between the percentage of lysine in the types of bread that were estimated by the chemical method (TNBS) and the PER of those types that were estimated by the biological method, where the correlation coefficient was r =0.91.