Production of anthocyanin-enriched flours of durum and soft pigmented wheats by air-classification, as a potential ingredient for functional bread

Pigmented wheats have roles in development of functional foods because of their high levels of anthocyanins, which contribute to reduction of postprandial glycaemic levels. This study tested air-classification for production of anthocyanin-rich fractions of durum and soft pigmented wheats for use in bread formulations, which provided a coarse fraction (CF) and a medium-fine fraction (MF). The greatest increases in anthocyanins and their components, and in yellow pigments and antioxidant capacity, were for the blue soft wheat CF and the purple durum wheat MF. By varying the air-flow inlet valve, more CF and MF were obtained, as 220CF and 178MF of blue and purple wheats, respectively. These showed increased total anthocyanins of 1.4-fold and 1.8-fold, and yellow pigments of 1.2-fold and 1.3-fold, respectively, compared to their relative micronised wholemeals. These were chosen for bread making. Anthocyanin levels were consistently increased in bread from blue 220CF and refined flour (3:7, w/w), while they were minimal in bread from purple 178MF and refined soft wheat flour (4:6, w/w). Significant reductions in estimated glycaemic index of these breads were observed, as 46% and 30%, respectively. Finally, enriched bread from purple durum wheat 178MF had a pleasant aroma and good taste.