Effects of low acyl and high acyl gellan gum on the thermal stability of purple sweet potato anthocyanins in the presence of ascorbic acid

This study investigated the different effects of low acyl (LA) and high acyl (HA) gellan gum on the thermal stability of anthocyanin-containing model beverage systems in the presence of ascorbic acid. The addition of gellan gum, especially HA, resulted in higher absorbance values, which suggested higher anthocyanin stability during heat treatment. The thermal stability of each anthocyanin was significantly improved by the addition of gellan gum (P < 0.05). Moreover, diacylated anthocyanins exhibited higher heat resistance than monoacylated anthocyanins. The molecular dynamics simulations revealed that the improvement in the anthocyanin stability following the addition of gellan gum was due to the binding between the gellan gum and the anthocyanins. HA was found to have stronger interactions with the anthocyanins than LA, which was attributed to the increased steric hinderance and flexibility caused by the acyl groups. In summary, we revealed that gellan gum can potentially be used to enhance the thermal stability of anthocyanins in beverages and identified the important role of the acyl groups of gellan gum in stabilizing the anthocyanins. These findings will broaden the applications of gellan gum and improve the popularity of anthocyanin-containing beverages. (C) 2018 Elsevier Ltd. All rights reserved.