Anthocyanins During Baking: Their Degradation Kinetics and Impacts on Color and Antioxidant Capacity of Bread

Anthocyanin-rich black rice powder was incorporated into bread, and the stability of two specific anthocyanins, cyanidin-3-glucoside and cyanidin-3-rutinoside, during baking was investigated. Various baking conditions included different baking temperatures (200, 220, and 240 °C) and baking durations (0, 2, 4, 6, 8, 10, and 12 min). Non-isothermal kinetic models were successfully established for the two anthocyanins in both bread crumb and crust. The derived degradation rate (kref) of cyanidin-3-glucoside and cyanidin-3-rutinoside in bread crumb at the reference temperature (Tref) of 65 °C were 2.49 × 10−5 and 1.93 × 10−5 s−1, respectively. The kref values of cyanidin-3-glucoside and cyanidin-3-rutinoside in bread crust (Tref = 125 °C) were 5.37 × 10−4 and 5.72 × 10−4 s−1, respectively. The color development of bread crust and crumb was measured and expressed as L*C*H° values. While the color of bread crust was significantly subjected to variations in oven operating parameters, the color of bread crumb was relatively less affected by baking conditions. The antioxidant capacity and total phenolic content of bread samples were measured using DPPH and Folin-Ciocalteu assays, respectively. Results showed that in bread crumb, both the antioxidant capacity and the total phenolic content decreased; however, an increase in both was observed in bread crust.