Protective effect and mechanism of action of xanthan gum on the color stability of black rice anthocyanins in model beverage systems

We investigated the effect and mechanism of action of xanthan gum (XG) on the color stability of black rice anthocyanins (BRA) in model beverage systems (pH 3.0) containing L-ascorbic acid under different conditions. The color stability of BRA was significantly enhanced in the presence of XG under accelerated storage conditions (40 degrees C), particularly at 0.25% (w/v). The degradation of BRA followed a first-order reaction rate (R-2 > 0.89) during storage and thermal processing conditions. The addition of XG effectively improved the storage stability of BRA in the presence of L-ascorbic acid, particularly at 4 degrees C in the dark. Moreover, the thermal stability of BRA was enhanced by XG under thermal treatment (80 degrees C, 90 degrees C and 100 degrees C). The FTIR spectrum, X-ray diffraction and molecular simulation results showed that the interaction between XG and BRA was driven mainly by hydrogen bonds and hydrophobic interactions, leading to the increased stability of BRA. Our study demonstrated the benefits of using XG to improve the color stability of BRA in model beverage systems, further expanding the practical application of XG in anthocyanin-rich beverages. (C) 2020 Elsevier B.V. All rights reserved.