Quality characteristics improvement of low-phenylalanine toast bread


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This study was designed to prepare and evaluate low-phenylalanine toast bread made from gliadin-free wheat flour and hydrocolloids. Wheat protein fraction (gliadin) rich in phenylalanine was extracted using aqueous alcohol solution for the production of low-phenylalanine wheat flour. Pectin, gum arabic and carboxymethylcellulose (CMC) were used separately to improve the quality of bread at levels of 1, 2 and 3%. Chemical, rheological, organoleptic, baking, staling and microstructure of bread were studied. Phenylalanine content of gliadin-free bread samples reduced by 43.2% compared with control. Separation of gliadin negatively affected the rheological properties of dough and baking quality of bread, while rheological properties, baking quality and staling were improved upon hydrocolloids addition. Microscopic examination of crumb structure revealed remarkable differences in control and treated breads. It was found that acceptable bread could be produced using gliadin-free wheat flour with the addition of pectin or CMC up to 2 and 3%, respectively.