Conversion and hydrothermal decomposition of major components of mint essential oil by small-scale subcritical water treatment

Tai Ying Chiou, Shiori Nomura, Masaaki Konishi, Chien Sen Liao, Yasutaka Shimotori, Miki Murata, Naofumi Ohtsu, Yoshihito Kohari, Wei Ju Lee, Tsung Yu Tsai, Yuichi Nagata, Tohru Saitoh

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Thermal stabilities of four major components (l-menthol, l-menthone, piperitone, and l-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: l-menthyl acetate, l-menthol, piperitone, and l-menthone. In individual treatments of mint flavor components, subsequent conversions of l-menthyl acetate to l-menthol, l-menthol to l-menthone, l-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.

Original languageEnglish
Article number1953
Issue number8
Publication statusPublished - Apr 2020


  • Conversion
  • Hydrothermal decomposition
  • Mint essential oil
  • Subcritical water treatment
  • Thymol

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemistry (miscellaneous)
  • Molecular Medicine
  • Pharmaceutical Science
  • Drug Discovery
  • Physical and Theoretical Chemistry
  • Organic Chemistry


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