Quality evaluation of essential oil from Nova Scotia-grown mint

The purpose of this project was to evaluate the potential of mint stands to be established in Nova Scotia, Canada and to produce commercially acceptable mint oil. Three species of plants were used in the establishment of the mint stands (Mentha spicata, Mentha piperita cv Black Mitchum and Mentha piperita cv Murray Mitchum). The plants were grown in two locations in Nova Scotia (Bible Hill and Maitland) over two seasons. The plants were harvested in each season at 3 different bloom stages (50%, 75% and 100%). The samples were steam distilled to recover the essential oil and complete quality analysis (specific gravity, refractive index and percent composition) of the oil performed to determine its viability as a commercial product. The oil recovered was unexpectedly low for all 3 plant varieties, ranging from 0.21--0.55% rather than the expected 2--4%. The specific gravity of the Mentha spicata at the 3 bloom stages ranged from 0.87--0.90 g/mL which corresponds to the literature value of 0.9 g/mL. The two peppermint cultivars were marginally acceptable with specific gravity values of 0.80--0.82 g/mL. All plants had acceptable refractive indices of 1.46--1.49. With respect to the two major components of mint oil (menthol and menthone) the 2 cultivars of peppermint had acceptable levels with menthol ranging from 31.84--41.49% and menthone ranging from 3.12--14.18%. The menthol:menthone ratios of the two cultivars of peppermint ranged from 2.25:1 to 12.12:1. Also completed was an antioxidant test trial to measure the effect, if any, of a commercial mint oil and its individual components as antioxidants. It was found that there were no significant differences between the mint oil components and the control with respect to antioxidant capacity.