2 METAL-IONS IMPROVE BRIGHTNESS IN WHEAT-DOUGH PRODUCTS AND AFFECT AQUEOUS DISPERSION OF GLUTEN

Zinc and aluminum ions at 0.05% of wheat flour, dry basis (7.4 and 18. 5 mmol/100 g, respectively), improved the brightness of raw and dried spaghetti and salt and alkaline noodles. They also retarded bacteria a nd yeast and mold growth in salt noodles held at 25 degrees C for two days as determined by total plate counts. Neither metal ion caused a c hange in noodle cooking quality, but they imparted a slight aftertaste in cooked noodles. Wheat flour dough mixed with 0.05% zinc or 0.025% aluminum ion (fwb), when kneaded in aqueous 0.1% calcium chloride, gav e gluten with increased brightness. Zinc and aluminum ions appear to c omplex with enzymic browning chromophores in wheat dough and gluten an d change their spectral properties. Zinc and aluminum ions affected th e dispersion of gluten in water at pH similar to 5.0 and facilitated i ts spray-drying, but they were not detrimental to baking quality, Citr ic and tartaric acids at 5 mmol/100 g of gluten (db) gave wet gluten w ith pH similar to 4.5, which improved its brightness and water dispers ibility.