Effect of L-proline on stability and in vitro digestive antioxidant capacity of mulberry anthocyanins in model beverages

Cyanidin- 3 - O -glucoside (C3G), the major anthocyanin in mulberry, is susceptible to chemical degradation and discoloration when exposed to ascorbic acid (AA). The protective effects of aspartic acid (Asp), valine (Val), and proline (Pro) on the stability of C3G when exposed to AA were investigated. The analysis o f degradation kinetics showed that Asp, Val, and Pro significantly enhanced ( p < 0.05) the stability of C3G at 40 °C for 7 d. With the addition of Pro, the half-life of the C3G was extended from 3 d to 7 d. Thermodynamic parameters indicated that the interaction between Pro and C3G, as well as the interaction between Pro and AA, was primarily through hydrogen bonding and van der Waals forces. Antioxidant activity assays in vitro revealed that the model beverage system supplemented with Pro exhibited high scavenging rates for 2,2-diphenyl-1-picrylhydrazyl radical (DPPH ● ) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation(ABTS ●+ ), which might due to the synergistic effects of Pro, C3G, and AA. In the model beverage system, adding Pro effectively enhanced the stability and antioxidant capacity of C3G. • In the presence of ascorbic acid, proline improved the stability of C3G. • In model beverages, proline could interact with C3G or ascorbic acid. • The addition of proline increased the antioxidant capacity of the model beverages.