蓝莓果汁饮料原花青素的热稳定性及降解动力学模型

Thermal stability and degradation kinetic model of proanthocyanidins in blueberry (Vaccinium spp.) juice beverage

【目的】研究蓝莓果汁饮料中原花青素的热稳定性及降解动力学特征,为蓝莓果汁饮料贮藏条件的优化及保质期预测提供参考。【方法】观察不同pH蓝莓果汁饮料中原花青素含量在有氧与充氮气条件下以不同温度处理时的变化情况,判断反应级数,运用动力学方程建立蓝莓果汁饮料原花青素降解模型。【结果】有氧条件下,蓝莓果汁原花青素在pH 5.8、4.6、2.2时降解反应活化能分别为25.34、18.77、16.80 kJ/mol,半衰期为1.91~4.58 d;充氮气条件下,蓝莓果汁原花青素在pH 5.8、4.6、2.2时降解反应活化能分别为56.70、26.35、19.36 kJ/mol,半衰期为1.90~15.79 d。【结论】在有氧或充氮气条件下,随着温度的升高和pH的降低,蓝莓果汁饮料原花青素的稳定性下降,原花青素降解反应的活化能和半衰期呈明显下降趋势;充氮气处理可以提高原花青素的稳定性,降解反应均符合一级反应动力学模型。通过验证试验发现:所建立的蓝莓果汁饮料原花青素降解动力学模型与实测值拟合程度较好(决定系数R^2≥60.25%)。

【Objective】We studied the thermal stability and degradation kinetics of proanthocyanidins in blueberry(Vaccinium spp.)juice to provide a reference for optimizing storage conditions and predicting the shelf life of blueberry juice.【Method】Changes in proanthocyanidins content in blueberry juice with different pH values were observed at different temperatures under aerobic or nitrogen-filled conditions and the reaction order was judged.Then,the degradation model of proanthocyanidins in blueberry juice was established using the kinetic equation.【Result】Under aerobic conditions,the activation energies of degradation reaction of proanthocyanidins in blueberry juice at pH 5.8,4.6 and 2.2 were 25.34,18.77 and 16.80 kJ/mol,respectively,and the half-life ranged from 1.91 to 4.58 days.Under nitrogen-filled conditions,the activation energies of degradation reaction of proanthocyanidins in blueberry juice at pH 5.8,4.6 and 2.2 were 56.70,26.35 and 19.36 kJ/mol,respectively,and the half-life ranged from 1.90 to 15.79 days.【Conclusion】With increase in temperature and decrease in pH value under aerobic or nitrogen-filled conditions,the stability of proanthocyanidins in blueberry juice decreased,while the activation energy and half-life of proanthocyanidins degradation reaction significantly decreased.Nitrogen-filled treatment can improve the stability of proanthocyanidins,and the degradation reactions were consistent with the first-order reaction kinetics model.Through verification experiments,it was found that the kinetic model of proanthocyanidins degradation in blueberry juice was well-fitted with the measured values(R^2≥60.25%).