Essential Oils: Technology and Processes

Lecture 2: Essential Oils & Healing

The minute droplets of oil in tiny pockets or glandular cells found in various parts of botanical are very volatile, that is, they easily evaporate, infusing the air with their characteristic aroma are called Essential Oils.

For many plants, essential oil is what gives the plant its aroma. The aroma can help deter predators like insects or herbivores. It has also been suggested that they play an important part in the transpiration and life processes of the plant itself, and as a protection against disease. They have been described as the ‘hormone’ or ‘life-blood’ of a plant, due to their highly concentrated and essential nature. Essential oils also play a vital role in the reproductive processes of plants and are useful during plant pollination. It is to be understood that not every plant produces an essential oil, and not every essential oil found within a plant has significant benefits. However, there are still plenty of powerful essential oils to go around. Just as plants use these compounds (essential oils) to protect themselves, we too can use the powerful, natural properties of essential oils to protect ourselves and promote a healthy body.

Every agrarian produce has some inherent complexities. The variable parameters are so enormous and mind boggling that to understand them one must start from basic agronomy of the produce leading to the by products; here essential oil is a by-product.

The benefits of each essential oil are largely determined by the kind of plant it comes from and the chemical properties it contains. Hence, the primary product is the aromatic plants/botanicals (because earlier the aroma or fragrance was the main consideration but now its also flavour and medicinal properties).

To start with making oils someone has to take an agro-commercial decision as to which crop to be grown in the given limitation than land, environment surrounding it, water and the farmer in that limited window.

The chemical composition of the essential oils produced in the plants, which determine their fragrance, are affected by factors such as the quality of seed, soil type, altitude, temperature and humidity: as determined by the amount of sunshine and rainfall in which the plants grow. Because of this, carefully choosing the geographic location, specific climate, and time of year for planting, growing, and harvesting plants will influence the quality of its essential oil. Since these parameters are dynamic and ever changing, plants must also be carefully planted, cared for, and closely watched by knowledgeable growers and farmer who understand the dynamic forces of working.

Like human beings, each plant is different so each plant’s properties will vary but to identify aggregation or broad categories have to be appreciated. So, first principle is identifying homogeneous lands on parameters of weather, soil, environmental and in close vicinity. Any differences in any of them have to be smoothened over; it is imperative to do so especially in cases of nutritional shortfalls. All plants require nutrition like humans and like in all patches of available land, there will be different nutritional deficiencies. So, to grow the right quality of herbs, a lot of agronomy knowledge gets involved. When the best techniques for planting, growing, and sustaining healthy plants are used, they contribute to a high-quality essential oil. In this range volume is not critical, quality of produce is important but like farmer is more at comfort with increased volumes than the yield quality. Better the knowledge one has, better one is able to understand the quality of product. That is reason we recommend organic farming with maximum possible knowledge of agronomy.

The second critical factor comes post-harvest. In addition to these factors, the time of harvesting and method of extraction when intervals between the different stages of the extraction process are involved can also affect the final fragrance of the essential oil. Harvesting is the easiest part but if one understands a “still” (commercial vessel to make EO’s) need around 700 -1500 kg of raw material to process. The plants properties and potency levels start decreasing from moment its cut. So logistically it’s important to consider the timings of cutting the crop, getting it transported to unit without substantial or minimal deformation of profile of product. Like we take example of roses, the crop that is cut, transported, leaves plucked and put in vessel before sunrise gives better quality of rose water and if it goes post sun rise or the longer the logistical process takes lesser is the fragrance. Now imagine our “still” for rose water is 500 litres; to fill it we require 250 kgs of rose petals (at optimum level). To get 250 kgs of rose petals, nearly 500 kgs of roses must get plucked, leaved and transported to vessel point by 6 /6.30 am. Imagine the logistics nightmare!

Depending on the season, time of year or even specific years may cause batches of the same oil to smell slightly different from each other or from the odour type that consumers are familiar with. In addition, the colour of the essential oils may vary slightly.

The production phase:

The vessel that is planted to extract EO’s must be as closest to raw materials –to reduce time lag as quality diminishes fast and which is not hard to imagine why as we all understand the difference between a living organism and dead organisms.

Traditional Distillation Unit
Traditional Distillation Unit

There has to be better coordination between the growing and distillation units. The unit must be clean, ready, with manpower, fuelled energy needs, and water- items it consumes in big quantities and can’t be stopped halfway.

It needs a team of technical people even in standby mode to reduce time lag, breakdowns, coordination. Delays, break down, shortage of energy sources (since mostly biomass is used —different matrix of items are used based on the need of heat the technical person decides) and lapse in water supply (which not only required in the vessel to generate steam but a lot more is needed to condense the steam in the coil to convert steam in liquid form) not only affect production cost but also the product quality.

The Distillation process

The technology:

Technology costs! But controlling parameters help in the quality of the oil. Like our 500-liter capacity rose water unit costs around INR 30 lacs but if we would have gone for MS same unit would cost INR 3-4 lacs and we would be stupid not to save money and we know its largest sized vessel dedicated only for rosewater while others use vessels across crops of MS and some even create rose water from scrapped tin containers of oil/ghee of 15 kg. The quality of “still” and dedicated vessels help in surface passivation intact in the vessel that affects the quality of the product i.e. essential oil

The extraction methods

Percolation or hydro diffusion: This method consists of feeding steam from the top to the bottom. It is faster and improves the quality of aromatic substances but also infuses essential oils with non-volatile substances. These products are referred to as “percolation oils.”

Supercritical carbon dioxide extraction: A modern technology that allows for the extraction of essential oils from plants when steam distillation is impossible, this method consists of passing a stream of CO2 at high pressure through aromatic plant materials to burst the essence pockets and extract the aromatic substances.

Enfleurage: Enfleurage is usually reserved for flowers with extremely low concentrations of essences (jasmine, mimosa, etc.). The flowers are soaked in absorbent fats that gradually become saturated with essence. The resulting pomades are used as is or dissolved by alcohol to obtain aromatic plant extracts called “absolutes.”

Extraction by solvents: Essences can also be extracted by volatile solvents (benzene). These essences are referred to as “concretes,” which become “concrete essences” once they have evaporated and “absolutes” when they are dissolved in alcohol. Concretes usually contain residual solvents (2-3%). These essences are therefore only suitable for olfacto-therapy.

In part three we will discuss the oil and what adds value to it what diminishes its value and that is critical to understand by intelligent buyers that like all diamonds are not equal so all oils can never be equal.


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