Hydrosols

Distilled or Extracted Specifically For Therapeutic Use - 2

The condenser is cooled by running water that flows from the bottom to the top, surrounding the internal pipe  with cold water, thus cooling the steam and converting it back into water and oil. That water is now a hydrosol. Most essential oils are lighter than water and will float on the surface of the hydrosol as it collects in the receiving vessel.

For this reason distillers use a Florentine flask to collect the output from the still. This specially designed container has two outflows . One drains the hydrosol from the bottom of the flask, allowing it to flow out and be collected ( which also serves to prevent the flask from overflowing ) and leaving the oil inside. The second outflow is near the top of the flask and is used only after the distillation is complete, when the oil is decanted through this pipe, leaving most of the remaining hydrosol in the Florentine.

Because distillation produces many times more hydrosol than oil, it is important that the two can be separated during the process. You couldn't make a Florentine large enough for all the water.This allows distillers to collect only the most therapeutic portion of the hydrosol ouput, usually the first 30 percent of a distillation run, although this varies from plant to plant. The hydrosol produced near the end of the run has  little therapeutic value, as most of the components coming over by this point are too lipophilic to remain in the water.

If distillers add the end product to the more potent early hydrosol, the waters are diluted, reducing both their aromas and their properties. Other parameters relevant to collecting  hydrosols can be found in a future chapter.In Hydro-distillation the plant material and water are combined in the still and the whole thing is then brought to a boil. The hot water draws out the oils, just as steam does and it is carried to the condenser and cooled into hydrosol and oil. This method is one of the oldest and has both benefits and drawbacks. First, it takes a huge amount of heat energy to bring a still-size volume of water and plant to a boil.

Just think how much longer it takes to boil. Just think how much longer it takes to boil a pot of potatoes than a kettle of water. Modern-day uses of this method are most current in countries where fire is used as the heat source or where electricity or gas are inexpensive. It is also the method used in India  for the production of certain attars and ruhs, (the Indian name for hydro-distilled oils), notably from the flowers like tuberose, jasmine, rose and lotus. For attars, the receiving vessel contains sandalwood oil, which becomes infused with the flower essence; in ruhs no sandalwood oil is used.

Those who distill by this method say that it produces a finer, more complete product, as hot water is cooler than steam and shocks the plant material less. Also, there is less conversation of alcohols to esters in the chemical makeup of the oil, and certain other fragile and highly odiferous molecules may also be better retained. 

I have had many hydrosols produced by hydro-distillation and can say that for the seed hydrosols, as well as some root and bark ones, this method does indeed seem to produce a richer hydrosol product but a much lower yield. With these tougher materials, the still can be filled with water and plant, then left to "stew" for twenty-four hours or more before distillation is begun. This seems to allow more before distillation is begun. This seems to allow more of the water-soluble components to be extracted. For other plant material  there seems to be much less difference in the products of therapeutic steam-versus water-distilling. There is still no agreement as to whether the life span is shorter or longer for hydro-distilled hydrolates versus the steam-distilled version.

Hydro-diffusion is an odd, if interesting, approach. In this case the steam inlet is at the top, above the plant material, and the outflow to the condenser is below. When you consider that steam is prone to flow up, not down, you can see what I mean by odd! The shape and dimensions of the still are different from those used in ffffsteam or hydro-distillation, being wider than tall, in this case.

This method has proved popular in countries where water is in short supply, as the steam is already partially cooled by its travel through the plants, so it requires less cooling in the condenser to be turned back into water and oil. Bear in mind that it takes a lot of water to keep a condenser cool, and many distillers heat their swimming pools, greenhouses, or homes by recycling this water. In hydro-diffusion, as in steam-distillation, the steam is created in an outside source, requiring less energy to produce than in hydro-distillation.

Many countries in Africa  are using hydro-diffusion, and their water scarcities are as legendary as their abundance of therapeutic plant material. so I am glad this method is available.The hydrosols and oils produced by this method are every bit as lovely as those produced by steam or water.

Distillation is such an art that you can count on your fingers and toes the number of truly great aromatherapy distillers in the world. They account for around 2 percent of the total global production of essential oils made each year. All the rest, whether organic or industrial, fall short by comparison. For this reason, and for the sheer fun of it, many aromatherapists today want to try distilling themselves . We are all alchemists at heart, and distilling on our won provides a much deeper understanding of the plants and the oils and hydrosols they produce.

I take all my students to an aromatherapy distillery as part of their training,: it is the only way to truly understand the level of work, commitment, and love required to produce our precious aromatics. This year they spent more than half a day in the forest, surrounded by black flies and mosquitoes, gathering just four hundred pounds of larch branches, tying them in bundles, and hiking them back out of the woods, fording streams and ditches.

This four hundred pounds only half filled the still, and after nearly six hours of distillation we produced just 270 milliliters of the exquisite pale green oil.

Read More...Distilled or Extracted Specifically For Therapeutic Use - 3

Reference: Hydrosols The Next Aromatherapy / Suzanne Catty