Evaluation of bread free of phenylalanine for phenylketonuria patients.

摘要

Phenylketonuria (PKU) disease is produced from deficiency of phenylalanine hydroxylase enzyme in children and lead to increase level amino acid (phenylalanine) in blood and it increase in excrete urine and the delay in diagnosis and treatment this disease lead to mental retardation, thus, the diet intake by these children must be that free of amino acid (phenylalanine). Modified starch is defined that changing in physical and chemical properties in native starch in order to obtain on a good desired characteristic starch and can be used in bakeries products. Thus, the purpose of this study was to modify corn and rice starch by microwave treatment at 2, 4 and 6 minutes and study the modification effect on chemical composition, P_H value, acidity, water binding capacity, swelling power, solubility, viscosity and amylose content. The results showed that in both modified corn and rice starch P_H value was decreased, while acidity was increased. In addition, water binding capacity, swelling power and solubility were increased, while viscosity was decreased Moreover, amylose content was increased. The best two treatment by microwave at 2 and 4 minutes were chosen and flat bread was prepared, then chemically analyzed, sensory evaluated and tested for bread staling. The results of sensory evaluation indicated that the best treatment for texture was in bread produced of modified corn starch treated at 2 min. microwave and also in bread produced of modified rice starch treated at 2 and 4 min. microwave compared to control. The best treatment for taste and general appearance were in bread produced of modified corn starch treated at 2 and 4 min. microwave and so in bread produced of modified rice starch treated at 2 min. microwave compared to control. The color and flavor were not significantly different between bread produced of modified corn and rice starch treated at 2 and 4 min. microwave and control (untreated). The results demonstrated that both modified corn and rice starch treated at 2 and 4 min. microwave led to delay staling of flat bread and improved freshness of flat bread.