Mineral composition, minerals bioavailability, and <i>in vitro</i> glycemic index values of whole wheat breads prepared from colored wheats

The technological properties, mineral contents, in vitro mineral bioavailability, and glycemic index (GI) values of breads made from whole wheat flours of colored wheats (red, purple, blue, and black) were evaluated. Purple wheat had the highest Farinograph stability, while black wheat showed a higher water absorption value, indicating superior rheological properties. The symmetry and crumb cell structure of whole wheat breads made from blue and black wheats were significantly (p<0.05) better than those of other varieties. The bread made from blue wheat had the highest loaf volume and the lowest firmness value. Significant differences (p<0.05) were observed among the bread samples in terms of mineral contents, Cu, Fe, K, Mg, Mn, P, Zn, and Se. The bioavailability values of K (74.15–92.66%,) followed by Se (43.27–64.77%), Cu (39.91–57.34%), and Mg (37.00–46.95%) were generally high across all bread types. GI, which measures postprandial blood glucose levels, was higher in the breads made from red, purple, and black wheats (71.49–72.03) compared to the blue wheat bread (63.64). In conclusion, the use of colored whole wheat flours, especially blue wheat, is an effective strategy for lowering the GI. Thus, colored wheats can be used to produce whole wheat breads with improved functional and nutritional characteristics as well as satisfactory baking quality.