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摘要
Japanese cornmint (Mentha canadensis L.) is a major essential oil crop grown in Asia, South America, and to a limited extent in eastern Europe. Japanese cornmint oil is the only commercially viable source for crystalline menthol. We hypothesized that the length of the distillation time (DT) will have an effect on Japanese cornmint essential oil content and composition. Therefore, the objective was to evaluate the effect of eight DTs (1.25, 2.5, 5, 10, 20, 40, 80, and 160 min) on essential oil content and composition. The essential oil content (0.43% to 1.06% range) reached maximum at 10 min DT; further increase in DT did not significantly increase essential oil content. The concentrations of alpha-pinene (0.14% to 0.76% range), beta-pinene (0.23-0.81), 3-octanal (0.19-0.34), limonene (0.69% to 1.53%), eucalyptol (0.06% to 0.12%), isopulegone (0.42% to 0.56%), and isomenthone (4.4% to 5.7%) were highest at 1.25 to 5 min DT and generally decreased to their respective minimums at 160 min DT. The concentration of menthone (4.3% to 6.3%) was highest at 1.25 min DT, decreased at 2.5 min, and was lowest at 10 to 160 min DT. The concentration of piperitone (0.98% to 1.27%) was lowest at 1.25 min DT and higher at 5 to 40 min DT compared with other DTs. The concentration of menthol (74% to 79%) was low at 1.25 min, then increased at 10 to 80 min DT, and reached a maximum at 160 min DT. Generally, the yield of most individual essential oil constituents was lower at 1.25 min DT relative to the other DT and reached maximum at 10 to 20 min DT. The yield of menthol was low at 1.25 to 2.5 min DT and rose at 5 min to 160 min DT. The results suggest that different DTs can be used to maximize recovery of certain constituents. Also, the results demonstrated that there are no oil yield gains after 20 min DT, which is much lower than the usual distillation time of 60 min or more. This study can be used as a reference when comparing reports in which different DTs were used.
- 出版日期2012-5
