Improvement of technological properties of wheat flour due to effects of thermal and mechanical treatments

Abstract

Secondary modification of roller milled wheat flour by planetary ball milling has been shown to have considerable effects on the chemical and microstructural properties of wheat flour. In this study, the effects of ball milling on the dough properties and the baking quality of flours from two wheat cultivars were studied. Several milling parameters such as rotation speed and grinding time were systematically altered and the modified flours were analyzed in the farinograph, by microscale extension tests with dough and gluten, and baking tests (10 g of flour). Modification by ball milling strongly increased the water absorption of the flours due to starch damage and, at high modification intensity, partial gelatinization of starch. In spite of increasing water absorption, the dough development time of intensely treated flour increased by a factor of 2.4 compared to untreated flour. However, the amount of wet gluten as well as the gluten index after moderate treatment was quite similar to the values of the base flour. With increasing intensity of modification, the specific loaf volume continuously decreased to less than 30% of the initial value. Crumb properties such as firmness and cohesiveness were also negatively affected. However, a positive effect was seen, when weakly modified flour was mixed with untreated flour. The addition of 7.5% weakly modified flour significantly increased the specific loaf volume as compared to the plain base flour. These findings show that weak mechanical modification can transform wheat flour functionality for baking applications to improve the bread quality.