Thermal degradation kinetics of ascorbic acid, thiamine and riboflavin in rosehip (Rosa canina L) nectar

Abstract In this paper, the loss of L-ascorbic acid, thiamine and riboflavin in rosehip nectar with the heating periods (0, 5, 10, 15, 20 and 30 min) at temperatures ranging from 70 to 95 °C is analyzed and experimental results are presented. Firstly, dried rosehip fruits were processed to rosehip nectar and then thermal treatment is performed. Liquid chromatographic (HPLC) method was used for the analysis of the contents of L-ascorbic acid, thiamine and riboflavin and examined compounds are thoroughly separated within 25 min. During thermal processing, degradation of L-ascorbic acid, thiamine and riboflavin in rosehip nectar were fitted to a first-order reaction kinetic model. Arrhenius relationship was used for the description of temperature dependence of reaction. Activation energies for L-ascorbic acid, thiamine and riboflavin between 70 to 95 ºC were found to be 55.30, 36.38 and 37.15 kJ/mol, respectively. To the best of the author’s knowledge, due to lack of study on the thermal degradation of L-ascorbic acid, thiamine and riboflavin in rosehip nectar, this manuscript will be the first reported study to enable future analysis.

摘要 本研究针对70℃至95℃温度区间内、不同加热时长（0、5、10、15、20及30分钟）下玫瑰果饮品（rosehip nectar）中L-抗坏血酸（L-ascorbic acid）、硫胺素（thiamine）与核黄素（riboflavin）的含量损失情况展开分析，并呈现相关实验结果。研究首先将干燥玫瑰果果实加工为玫瑰果饮品，随后对其实施热处理。采用高效液相色谱法（HPLC）对三种目标物质的含量进行测定，目标化合物可在25分钟内实现完全分离。在热处理过程中，玫瑰果饮品中L-抗坏血酸、硫胺素与核黄素的降解过程均符合一级反应动力学模型。本研究采用阿伦尼乌斯关系（Arrhenius relationship）描述反应的温度依赖性。经测定，70℃至95℃区间内，L-抗坏血酸、硫胺素与核黄素的活化能分别为55.30、36.38及37.15 kJ/mol。据作者所知，目前尚无针对玫瑰果饮品中上述三种物质热降解过程的相关研究，因此本研究为首次报道相关成果，可为后续相关分析提供参考依据。