| Physicochemical properties of isolated wheat starch treated with ozone gas (1,500 ppm at 2.5 L/minute) for 30 minutes and starch isolated from ozone treated flour (1,500 ppm for 45 minutes at 2.5 L/minute) were evaluated. Chemical analysis of starch isolates indicated depolymerization of high molecular weight amylopectins with a subsequent increase in low molecular weight starch polymers as a result of starch hydrolysis. Ozone oxidized starch isolates had elevated levels of carboxylic groups and a decrease in total carbohydrate content in amylopectin fractions. ¹H NMR results indicated formation of keto group and beta-glucuronic acid.;Ozone oxidized lipids increased brightness, reduced the yellow hue, and increased peak viscosity and setback viscosity of bread flour. Bread made from wheat flour treated with ozone at 1,500 ppm for 4.5 minutes and bread made from wheat flour blended with 10% w/w fully ozonated wheat flour had good crust color, a whiter crumb, and had more crumb cells, which resulted in a greater specific volume of the bread when compared with control wheat flour. Extended exposure of wheat flour to ozone (9--45 minutes) and higher blends of fully ozonated wheat flour (20--100% w/w) deteriorated wheat flour functionality and quality of bread.;Experiments were conducted to compare the efficacy of potassium bromate with that of ozone in bread making. In the first experiment, flour was treated with ozone at 1,500 ppm (at 2.5 L/minute) for 2, 4.5, 9, and 18 minutes. In the second experiment, flour was fully treated with ozone at 1,500 ppm (at 2.5 L/minute) for 45 minutes and then blended with control flour at concentrations from 5 to 30% (w/w). High performance size-exclusion chromatography indicated an increase in sodium dodecyl sulfate buffer insoluble polymeric proteins in flour exposed to ozone (1,500 ppm for 45 minutes). Bread made from flour treated with ozone for 2 to 4.5 minutes significantly increased specific loaf volume, and bread that was made from flour blended with fully ozonated flour at 5 and 10% (w/w) was not significantly different for specific volume when compared with bread made with flour containing potassium bromate. |
