[关键词]
[摘要]
本文研究了不同贮藏条件对草莓汁中维生素C降解的影响,分别采用玻璃瓶和PET瓶为包装材料对草莓汁在不同贮藏温度(4 ℃、20 ℃和37 ℃)下维生素C的降解规律进行分析,并分别建立动力学模型。结果表明:草莓汁中的维生素C对热不稳定,随贮藏温度的升高,降解速率增大,半衰期减小;同一贮藏温度下,PET瓶的降解速率大于玻璃瓶;玻璃瓶和PET瓶中草莓汁维生素C的降解均符合一级动力学模型,其反应活化能分别为32.04 kJ/mol和28.26 kJ/mol。两种包装材料预测模型的验证值与实测值的相关系数R2>0.99,表明了模型的有效性,可用于预测任意温度下贮藏的维生素C含量及草莓汁货架期。同时对草莓汁中维生素C活化热力学函数(ΔG≠,ΔH≠,ΔS≠,K≠)的值进行了计算分析,为阐释维生素C降解机制提供了依据。
[Key word]
[Abstract]
The effects of different storage conditions on the degradation of vitamin C in strawberry juice was investigated, the contents of vitamin C in strawberry juice which was stored in glass or PET bottles at 4 ℃, 20 ℃ and 37 ℃ were analyzed during the whole storage period. Corresponding kinetic models were also established. The results showed that the degradation rate of vitamin C in strawberry juice increased with the increase of storage temperature and the half-life period declined accordingly. At the same storage temperature, the degradation rate of vitamin C in PET bottles was higher than that in glass bottles. The degradation kinetics of vitamin C in strawberry juice from glass and PET bottles followed by first-order kinetic model, with the reaction activation energies of 32.04 kJ/mol and 28.26 kJ/mol, respectively. The correlation coefficient between the verified values of prediction models and the measured values was R2 > 0.99, indicating the validity of the model. It means the equation could be used for estimating the first-order losses of vitamin C in the stored strawberry juice, at any specific temperature and degradation ratio. The thermodynamic functions of activation (ΔG≠, ΔH≠, ΔS≠, and K≠) were determined and can provide valuable information for degradation mechanism of vitamin C.
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[基金项目]
江苏省农业科技自主创新资金[CX(18)2028]