Yield and Composition of Oil from Japanese Cornmint Fresh and Dry Material Harvested Successively

A field experiment was conducted to evaluate the effect of harvest time and drying on Japanese cornmint (Mentha canadensis L.) cultivars Arvensis 2 and Arvensis 3 to optimize technology. Biomass yields were comparable to those reported in the literature. Arvensis 2 had greater oil content (0.78%) than Arvensis 3 (0.59%), while Arvensis 3 had higher concentrations of(-)-menthol (71.9%) and (-)-menthone (13.5%) than Arvensis 2(61.7 and 9.4%, respectively). Arvensis 3 had higher fresh biomass (34,289 kg ha(-1)) than that of Arvensis 2 (23,929 kg ha(-1)). Dried biomass of the two cultivars was not significantly different. Higher oil yields were achieved from the fresh biomass of Arvensis 2 (108.7 kg ha(-1)), and lower from the dried biomass of Arvensis 2 (78.2 kg ha(-1)) and the fresh biomass of Arvensis 3 (84.3 kg ha(-1)). The concentration of(-)-menthol in the cultivars was higher at harvests 4 (69.3%) and 5 (67.7%), and lower at harvests 2 (63.6%) and 3 (64.7%). The yield of(-)-menthol was highest in harvest 4 (116.2 kg ha(-1)), lower in harvest 3 (78.4 kg ha(-1)) and lowest in the first harvest (19.1 kg ha(-1)). In northern Mississippi (or in other areas with similar latitude and environment), cornmint for production of (-)-menthol should be harvested in late July. For highest biomass yields, Arvensis 3 should be harvested in mid-July, whereas Arvensis 2 should be harvested in late July. The essential oil profile of M. canadensis in this experiment was more desirable (with respect to (-)-menthol concentration) than the profile of two commercially available M. canadensis oil samples from other countries, which should make the oil produced in southeastern United States easily marketable.