为探究不同结构有机酸对桑椹花色苷的辅色作用及其热稳定性的影响，采用超高效液相色谱-质谱法分析花色苷组成，以对羟基苯甲酸、原儿茶酸、没食子酸、绿原酸、苹果酸为辅色剂，考察pH值、温度、有机酸质量浓度对辅色反应的影响，并分别在60、70、80 ℃水浴中模拟食品中花色苷的热降解过程，探究热降解动力学规律。结果表明，在pH=3.5、20 ℃、960 mg/L质量浓度条件下，“增色效应”和“红移效应”达到最大，辅色效果依次为苹果酸>绿原酸>没食子酸>原儿茶酸>对羟基苯甲酸，苹果酸比空白组Aλmax增加45.04%。反应化学计量比（n）、平衡常数（K）、吉布斯自由能ΔG°显示辅色过程均自发进行，苹果酸的平衡常数（K）最大，吉布斯自由能ΔG°最小，分别为26.85、-8.02 kJ/mol。热降解实验表明添加有机酸能延长花色苷半衰期（T1/2），减小降解常数（k），60 ℃时，没食子酸可将花色苷溶液半衰期（T1/2）从17.50 h延长至26.23 h，降解常数（k）从6.6×102 min-1减小至4.4×102 min-1。因此，有机酸辅色作用有助于提高桑椹花色苷的稳定性。

The effects of different organic acids on the pigmentation and thermal stability of anthocyanins from mulberries were investigated. First, UPLC-MS/MS was used to analyze the composition of mulberry anthocyanins. Then, 4-hydroxybenzoic acid, protocatechuic acid, gallic acid, chlorogenic acid, and malic acid were used as co-pigments to determine the influence of pH, temperature, and organic acid concentration on the pigmentation of the mulberry anthocyanins. The thermal degradation of anthocyanins in food was simulated in water baths at 60, 70 and 80 ℃ to explore the effects of the organic acids on the thermal degradation kinetics of the mulberry anthocyanins. The most significant color enhancement and red-shifting effects were observed at anorganic acid concentration of 960 mg/L, pH of 3.5, and temperature of 20 ℃. The co-pigmentation effects of the five organic acids were in the following order: malic acid>chlorogenic acid>gallic acid>protocatechuic acid>4-hydroxybenzoic acid. Compared with that of the blank group, the absorbance at λmax of the group treated with malic acid increased by 45.04%. The stoichiometric ratio (n), equilibrium constant (K), and Gibbs free energy (ΔG°) indicated that the co-pigmentation reactions were all spontaneous. Malic acid, demonstrating the best co-pigmentation effect, had the largest K value (26.85) and the smallest ΔG° value (-8.02 kJ/mol). Through degradation experiments, it was found that the addition of organic acids could prolong the half-life (T1/2) of the anthocyanins and reduce their degradation constant (k). At 60 ℃, gallic acid prolonged the T1/2 of the anthocyanins from 17.50 h to 26.23 h and reduced the k value from 6.6×102 min-1 to 4.4×102 min-1. Therefore, co-pigmentation with organic acids can effectively improve the stability of anthocyanins from mulberries.

广东省重点领域研发计划项目（2020B020225005）；广东省农业科学院“十四五”农业优势产业学科团队建设项目（202119TD）