School of Regional Innovation and Social Design Engineering, Kitami Institute of Technology, Koen-cho, Kitami, Hokkaido 090-8507, Japan.
Department of Biotechnology and Environmental Chemistry, Kitami Institute of Technology, Koen-cho, Kitami, Hokkaido 090-8507, Japan.
Molecules. 2020 Apr 22;25(8):1953. doi: 10.3390/molecules25081953.
Thermal stabilities of four major components (-menthol, -menthone, piperitone, and -menthyl acetate) of Japanese mint essential oil were evaluated via subcritical water treatment. To improve experimental throughput for measuring compound stabilities, a small-scale subcritical water treatment method using ampoule bottles was developed and employed. A mixture of the four major components was treated in subcritical water at 180-240 °C for 5-60 min, and then analyzed by gas chromatography. The results indicated that the order of thermal resistance, from strongest to weakest, was: -menthyl acetate, -menthol, piperitone, and -menthone. In individual treatments of mint flavor components, subsequent conversions of -menthyl acetate to -menthol, -menthol to -menthone, -menthone to piperitone, and piperitone to thymol were observed in individual treatments at 240 °C for 60 min. As the mass balance between piperitone and thymol was low, the hydrothermal decomposition of the components was considered to have occurred intensely during, or after the conversion. These results explained the degradation of mint essential oil components under subcritical water conditions and provided the basis for optimizing the extraction conditions of mint essential oils using subcritical water.
采用亚临界水法处理评估了留兰香油的 4 种主要成分（薄荷脑、薄荷酮、胡椒酮和乙酸薄荷酯）的热稳定性。为了提高测量化合物稳定性的实验通量，开发并采用了一种使用安瓿瓶的小规模亚临界水法处理方法。将这 4 种主要成分的混合物在 180-240°C 的亚临界水中处理 5-60 分钟，然后通过气相色谱进行分析。结果表明，热阻从强到弱的顺序为：乙酸薄荷酯、薄荷脑、胡椒酮和薄荷酮。在薄荷风味成分的单独处理中，在 240°C 下处理 60 分钟时，观察到乙酸薄荷酯向薄荷脑、薄荷脑向薄荷酮、薄荷酮向胡椒酮和胡椒酮向百里香酚的后续转化。由于胡椒酮和百里香酚之间的质量平衡较低，因此认为在转化过程中或之后，这些成分发生了强烈的热分解。这些结果解释了亚临界水条件下薄荷油成分的降解，并为使用亚临界水优化薄荷油提取条件提供了依据。
