Dhuique-Mayer Claudie, Tbatou Manal, Carail Michel, Caris-Veyrat Catherine, Dornier Manuel, Amiot Marie Josephe
Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Département PERSYST UMR 95 Tropical Food Quality, TA B-95/16, 73 Av. J.F Breton 34398, Montpellier Cedex 5, France.
J Agric Food Chem. 2007 May 16;55(10):4209-16. doi: 10.1021/jf0700529. Epub 2007 Apr 24.
The thermal degradation kinetics of vitamin C, two carotenoids (beta-carotene and beta-cryptoxanthin), and hesperidin, as a function of temperature, were determined for Citrus juice [Citrus sinensis (L.) Osbeck and Citrus clementina Hort. ex Tan]. The influence of dissolved oxygen on the rate of ascorbic acid degradation was also assessed. Analysis of kinetic data suggested a first-order reaction for the degradation of vitamin C and carotenoids. The kinetics parameters Dtheta, z, and Ea have been calculated. Following the Arrhenius relationship, the activation energy of ascorbic acid was 35.9 kJ mol-1 and agreed with the range of literature reported value. The results on vitamin C and carotenoids from citrus juice made it possible to validate the predicting model. Thermal degradation of carotenoids revealed differences in stability among the main provitamin A carotenoids and between these and other carotenoids belonging to the xanthophyll family. The activation energies for the two provitamin A carotenoids were 110 and 156 kJ mol-1 for beta-carotene and beta-cryptoxanthin, respectively. On the other hand, no degradation of hesperidin was observed during thermal treatment. Finally, the vitamin C in citrus juice was not as heat sensitive as expected and the main provitamin A carotenoids present in citrus juice displayed a relative heat stability. The high-performance liquid chromatography-diode array detection-mass spectrometry analysis of degradation products showed that the isomerization of the epoxide function in position 5,6 into a furanoxide function in position 5,8 was a common reaction for several xanthophylls. These findings will help determine optimal processing conditions for minimizing the degradation of important quality factors such as vitamin C and carotenoid in citrus juice.
测定了橙汁[脐橙（Citrus sinensis (L.) Osbeck）和克莱门氏小柑橘（Citrus clementina Hort. ex Tan）]中维生素C、两种类胡萝卜素（β-胡萝卜素和β-隐黄质）以及橙皮苷的热降解动力学与温度的关系。还评估了溶解氧对抗坏血酸降解速率的影响。动力学数据分析表明，维生素C和类胡萝卜素的降解为一级反应。计算了动力学参数Dθ、z和Ea。根据阿伦尼乌斯关系式，抗坏血酸的活化能为35.9 kJ mol-1，与文献报道值范围相符。橙汁中维生素C和类胡萝卜素的结果使得验证预测模型成为可能。类胡萝卜素的热降解揭示了主要维生素A原类胡萝卜素之间以及它们与属于叶黄素家族的其他类胡萝卜素之间稳定性的差异。两种维生素A原类胡萝卜素β-胡萝卜素和β-隐黄质的活化能分别为110和156 kJ mol-1。另一方面，热处理过程中未观察到橙皮苷的降解。最后，橙汁中的维生素C不如预期的那样对热敏感，橙汁中存在的主要维生素A原类胡萝卜素表现出相对的热稳定性。降解产物的高效液相色谱 - 二极管阵列检测 - 质谱分析表明，5,6位环氧官能团异构化为5,8位呋喃氧化物官能团是几种叶黄素常见的反应。这些发现将有助于确定最佳加工条件，以尽量减少橙汁中维生素C和类胡萝卜素等重要品质因素的降解。
