Regarding Hydrosols from Patricia Cruz, Questions about Distillation:
1.Q. Does it matter what type of plastic containers (clear, pet or high density) in which you bottle your hydrosols?
A. We would prefer that you bottle your hydrosols in glass or in the aluminum bottles that have an essential oil protective liner. Plastic bottles are okay for short term storage or in the home or bathroom where you don't wish a breakable glass container. I also carry a 2 oz or 4 oz glass spray bottle of hydrosol in my purse for those on the road needs and hot flashes.
2. Q. Why is distilling Rosemary just in bloom better than when it has bloomed?
A. Read "The Aromatic News" Autumn 2000. You will note that the best components are in the Rosemary plant when it is fully flowering. The cineol content is higher and the camphor normally nonexistent. However, if you want the camphoraceous Rosemary hydrosol for skin treatment or scalp use, then by all means distill after bloom.
3. Q. What does head notes and tail notes mean? I can't discern any difference from the beginning to the end of distillation.
A. The head note is detectable at the immediate start of the distillation. It is usually sweeter than later, it is "higher", the pH will also be lower, there will be a rush of the essential oil. As the distillation proceeds you will get a more mature scent and then generally a vegetative/greenish note called the tails. Also, after the Body of the scent has passed, the pH begins to rise. This means you are distilling too much and the hydrosol is becoming water rather than hydrosol.
4. Q. Does water temperature of the water in the condenser have anything to do with how fast the hydrosol is recovered? (or comes out)?
A. Yes, it is very important that you keep the condenser water warmer rather than colder. You want to keep the temperature of the steam into the pot at about 212°F. while the condenser water is more like body temperature 100°-150°F. The warmer the condenser water the smoother will be the condensation. You don't want it either too fast (too hot or too slow (too cold).
5. Q. Is the first half or third of the distillation better than the hydrosol that comes out from the last couple of hours?
A. Quality of the hydrosol has to do with the pH, the odor, the taste, the quality of the plants that you started with, whether they were picked appropriately or not, and many other factors that we have discussed before. In a smaller still (5-25 gallons), it should take no more than 2.5 hours from the time that the hydrosol begins to come over to completion. Of course, there are other factors such as the density of the plant, the part of the plant, etc. When the scent of the hydrosol begins to get green and vegetative it is time to stop.
6. Q. We have a friend with a PhD in Chemistry. He does not do GC/MS. Is there some kind of testing he could do with the hydrosols?
A. The basic task of monitoring and testing hydrosols involves the detection of organic components in the water and measuring their concentration. Hydrosols can be injected directly onto a GC column but often this does not produce a satisfactory result. Please read Spring 2001 issue of The Aromatic News and you will find that you can use the following types of tests to examine the hydrosols: liquid-liquid extraction; solid phase extraction; liquid-solid partitioning; purge and trap; and static and dynamic headspace extraction.
7. Q. Why do we need to test the pH of the hydrosols?
A. There are several reasons to test the pH (acidity/ alkalinity) of your hydrosol during the distillation process. Mainly, it tells you if you are distilling with too much steam and if you are getting close to the pH of water. If your pH is close to 7, water, then you have distilled too long and you don't have hydrosol anymore you have water. Also, a pH close to 4-5 is acid, and resembles the pH of human skin. This acidity is helpful in preserving the hydrosol without the addition of any other substance. After storage, a change in pH can signal the growth of bacteria in your product.
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