Production of Melissa Oil in Ireland

Melissa Oil Production
in Ireland

Melissa oil production can be divided into two main processes:

Crop production

Field establishment
Soil fertility
Weed control
Harvesting
Climate/soil type

Oil extraction

The still
Distillation cycle
Oil yield
Storage
Production

Crop production

Field establishment

To help reduce the perennial weed population, a good cover crop such as cereals or potatoes is grown prior to the planting of the Melissa herb.

Melissa plants from a field no longer used for oil production are lifted and divided into smaller plants before being planted in the new field. Planting was previously done by hand into preformed ridges. However, from 1999 an adapted potato planter has been used.

Autumn is the best time for planting a new crop. However, if the rains come early making planting conditions difficult, planting will take place in the spring.

Soil fertility

Melissa plants require soil with a high organic matter content, therefore much farmyard manure is incorporated into the soil prior to planting. This source of nutrition rarely lasts the full growing season. Therefore an additional source of nitrogen, phosphorus and potassium is often required.

Weed control

The control of weeds is achieved by mechanical methods, mainly inter-row rotating, harrowing and steerage hoeing. Occasionally, depending on the season, flame weeding is used. To achieve the maximum benefits of mechanical weeding it is important that the Melissa plants are planted accurately in the straight ridges.

As yields of Melissa oil are low, large areas of land have to be planted. Subsequently these areas require regular and efficient weeding to ensure that profits are not lost on labour costs.

Harvesting

There are two harvests per year, one in late June, which gives a low oil yield, and one in late August which yields almost twice as much oil.

Climate/soil type

It is a typical gulf stream Atlantic climate, with mild wet winters and cool wet summers. The annual rainfall is approximately 1000mm. The average temperatures range from 2-9°C in the winter and 10-18°C in the summer.

The soil type is shale/alluvial, being mildly acidic and very stony.

Oil extraction

The still

The purpose-built still has been much improved and developed in the last five years. It has an overall size of 3 cubic metres and an internal capacity for approximately 100 kilos of fresh Melissa. It operates at atmospheric pressure.

Distillation cycle

An oil-fired boiler supplies steam to the system. After 25 minutes oil vapour will begin to be produced. This vapour is cooled and collected by passing it through a plate condenser. After 40 minutes this will result in approximately 30 litres of distillate. At this stage the oil has not separated from the water but remains as an emulsion.

A second distillation is necessary to isolate the oil, using cohobation equipment. After 30 minutes most of the oil, between 8-17ml, can be isolated from the distillate using a pipette.

Melissa oil yield

Generally there are between 10-15 distillations per day, which will result in between 500-750ml of oil per acre of planted crop, depending on soil fertility and plant age.

Melissa oil storage

Melissa oil extracted from mature plants in a temperate climate is stable when kept in dark glass bottles at 4°C. Gas Liquid Chromatography (GLC) analysis over two years or more shows negligible changes.

Production

Production yields on average between 2 and 4 litres of Melissa oil each year depending on the size of crop planted. However, despite its proven qualities and medicinal benefits, there is difficulty maintaining sufficient sales and an increase in production cannot be justified at present.