Spearmint Mentha spicata Essential Oil (Egypt & China)

Botanical Origin:

Common name: Spearmint

Latin name: Mentha spicata Huds.

Family: Lamiaceae

Other names:

Engl.: spearmint, garden mint, menthol mint, silver mint. Deu.: Grüne Minze, Ähren-Minze, Bocksbalsam, Katzenkraut, Wilde Pfefferminze. Suom.: viherminttu. Sven.: grönmynta, spetsmynta, spirmynta. Fran.: menthe verte, baume vert, menthe romaine. Span.: menta romana, yerbabuena. Pharm.: herba menthae acutae. Bot. syn.: Mentha aquatica L. var. crispa (L.) Benth., Mentha cordifolia Opiz es Fresen., Mentha crispa L., Mentha viridis (L.) L..

Several varieties of Mentha spicata Huds (M. viridis L.) e.g.:

1. spicata Huds. var. tenuis (Michx) Briq. (as in North America)
2. spicata Huds. var. trichoura Briq. (as in England)
3. spicata Huds. var. crispate (Schard.) Briq. (as in Germany)
4. verticillata L. var. strabala Briq. (as in Russia)

Description:

Spearmint resembles peppermint but does not grow quite as tall; spearmint stems are not as long as those of peppermint, but they stand more erect.

The lance-shaped leaves are longer, narrower, lighter green in color, and either without stems or with only very short ones.

Instead of being thick and blunt, the flowering spikes are more sharply pointed, long and narrow; thence the designation spearmint.

Range & Habitat:

Spearmint is naturalized from Europe and is found in roadsides and waste places, usually in damp soils and sunny positions.

Spearmint may be grown in a wide range of soils, loamy upland soil or various types of muck (characteristic of drained but not over drained, former swamp lands) being most suited.

Planting & Cultivation:

The ground is prepared as for corn or other grain crops, i.e., by plowing, disking several times, harrowing, dragging with a planker, and fertilizing. the better fitted the soil, the cheaper it is to eradicate weeds after planting.

The planting is done mainly by hand and usually takes place either from October to November, or in the spring. The rows are spaced 36 to 42 in. apart. The rootstocks are laid overlapping one another in furrows, and soil is dragged over them. Many acres of spearmint are propagated annually by means of young plants. It is claimed that this method has certain advantages; for instance, the fields may be cultivated right after transplanting. During late June and July, the young plants reach a height of 6 in., and are then transplanted with a cabbage planting machine.

As in the case of peppermint, the growers recognize two stages of spearmint plantings, namely the “row mint,” which consists of one-year-old plantings, and the “Meadow mint” which consists of fields two or more years old. “Meadow mint” may be weeded in the early stages by machines resembling the common harrow, but later, as it grows higher, all weeding must be done by hand. Growers rotate spearmint in a three-year cycle, because after that the yield of oil becomes uneconomical. Rotation should be done with corn, potatoes, or onions before mint is replanted.

Harvesting and Preparing for the Market:

Like peppermint, spearmint contains a maximum amount of oil during the flowering stage, which lasts several days. The harvesting is preferred to be done on dry, warm days.

After maximum bloom, the oil content decreases rapidly. “Meadow spearmint” flowers in late July and early August; whereas “row spearmint” reaches that stage about a month later.

The plants are cut with a mowing machine and left on the ground to dry for 48 hr. or longer, depending on the weather. The drying must not progress far enough to make the leaves too brittle as handling of the hay would result in a considerable loss of leaves by shattering. The dried material is raked, bunched, loaded on wagons with a hay loader or pitchforks, and hauled to the distilleries.

Yield:

3000 lb. charge yields about 20 lb. of oil. This yield is slightly higher than that of peppermint. One acre of spearmint may yield from 35 to 40 lb. of oil.

Method of Extraction:

By Steam distillation.

Distillation of a batch requires in general 45 to 60 min., but longer if the plant material is wet, e.g. distilling a 3000lb charge requires 35 to 50 min.

Notes:

• There is very little difference between spearmint oil distilled from “row mint” –the one year old mint- and “meadow mint” –the two or more years old.
• Crude spearmint oil often contains heavy metals, which can be removed readily by the usual method of treating the oil with tartaric acid.
• Resinification readily takes place in this oil. In normal oils the specific gravity and carvone content are in direct proportion. If an oil shows a high specific gravity and a carvone content lower than should correspond to this high gravity, resinification is indicated. A harsh odor and flavor, characteristic of such oils, confirms the suspicion.