###### Abstract  
Purple-colored wheat bran was blended with flour at different ratios. The dough mixing characteristics of the flour-bran blends and quality characteristics and antioxidant activity of the bread prepared with the blends were investigated. Additionally, response surface methodology (RSM) was used to optimize the formula and processing conditions for the bread prepared with the blend at 30% bran. Solvent retention capacity (SRC), as a quality characteristic of the blends, showed that water absorption and damaged starch contribution increased proportionally as the bran blending ratio increased. Dough mixing patterns of blends determined by a mixograph exhibited deteriorated gluten strength by increasing the bran blending ratio. The total phenolic and anthocyanin contents and antioxidant activity (ABTS and DPPH radical scavenging activity) of the bread increased proportionally as the bran blending ratio increased. RSM analysis revealed that the best-fitted model for the results was a quadratic polynomial model with regression coefficient values close to or more than 0.900 for all responses. Optimized conditions were 68.1 g water, 4.0 min mixing time, and 67.3 min fermentation time. Overall, purple-colored wheat bran was successfully applied to produce bread with healthy functional properties by controlling water and mixing time.  
purple-colored wheat bran; flour-bran blend; bread; antioxidant activity; response surface methodology; optimization Article
variety has a ten times higher antioxidant capacity than regular wheat and is rich in minerals [10]. A white wheat variety, \"Baekgang\", suitable for making bread, was also released to increase the Korean domestic wheat self-sufficiency rate [11].  
Numerous studies have been conducted on the application of whole wheat and bran in bakery products. [PERSON] and [PERSON] [12] examined changes in the phenolic content or antioxidant activity of breads during their production using colored whole wheat flour. In this study, the levels of free phenolic compounds increased during mixing, but those of bound phenolic compounds slightly decreased after fermentation for 30 min and significantly increased after fermentation for 65 min and during baking. The total antioxidant activity also showed a trend similar to that of the total phenol content. When making bread by adding up to 20% colored wheat bran, the dough weakens, moisture loss increases during baking, and the bread volume decreases with increasing proportions of bran [13]. However, studies using Korean domestic wheat flour and purple-colored wheat bran are scarce. Compared to imported wheat, Korean domestic wheat has advantages in food safety due to its low residual pesticide content, the short transportation distance, and the fresh consumption without long-term storage. [10]. To improve the quality of products formulated with wheat bran or whole wheat flour, dough improvers are commonly used, resulting in increased production costs. However, consumers favor products with lean formulas because of clean labeling. Thus, wheat bran pre-treatments such as hydration, extrusion, and fermentation are also used [14; 15; 16], resulting in increased production costs. Studies on controlling the primary ingredients or processing conditions are scarce. Therefore, it is worth investigating the effects of the primary ingredient or processing factor on the quality of the final product, for improving the quality of the flour-bran-blended bread.  
In this study, the physicochemical and dough mixing properties and bread-making performance of a blend of Korean domestic wheat flour with purple-colored wheat bran at different blending ratios were determined. The antioxidant activity of the bread was analyzed. In addition, significant processing factors were identified and optimized to improve bread quality while increasing antioxidant activity.