Vacuum distillation...experiment results and silly question.

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nzhuhu
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Vacuum distillation...experiment results and silly question.

Post by nzhuhu » Tue Mar 10, 2020 12:11 am

Dear every one,
I am trying vacuum distillation technic. My kit is glass vacuum rated ( borisilicate 3.3 ) with dry vacuum pump, chiller i use ice with water pump ( usually run at 15 degree celcius through condenser ). I also place empty pot in middle of vacuum line ( connect from vacuum pump to distill kit ) to secure the vacuum also stop the vacuum pump from running all the time.
My fist test with grapefuit ( white meat ) and lemongrass. Here is my parameter:
Chopping all material to 3mm cubic put them in the pot together with water ( submerging material in water ).
Turn on vacuum pump to sucking all air in side the distill system and the empty pot also. Reaching the requiment: for negative gauge -26inHg/-88kPA/-12.79PSIG/87% vacuumed air , for positive gauge 3.8inHg/13.17kPA...just for easy convert for your convenient.
Now i start the heating, i set it heat up to 63 degree celcius and i get bubble....at 70 degree i get heavy boiling. I let it stay at 63 degree
Every 1hr the vacuum is moving up so i have to vacuum again for 3 mins, after that degree of the pot is droping down from 59 to 6p degree, the heat will back up to 63 in 10 mins.
Yes i get liquid coming out at collecting pot with the smell almost the same as raw yeast of the fruit but there is no oil even i am using reparate funnel. I suspect i collect hydrosol water, please correct me. Here i am getting confuse, do i have to make the water going into heavy boiling phase ? Or i must have to consider the boiling point of the oil which i plan to extract ?
Please do teach me. Thank you very much.

Windswept
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Re: Vacuum distillation...experiment results and silly question.

Post by Windswept » Tue Mar 10, 2020 9:51 am

So, my understanding of this kind of separation is that running the still will move alcohol, then water into the collection flask from the boiling flask until you are left with the hydrosol (in the boiling flask).
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OtisT
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Re: Vacuum distillation...experiment results and silly question.

Post by OtisT » Tue Mar 10, 2020 8:01 pm

Nzhuhu,
I have a guess as to why you are getting hydrosol but not essential oils. I think if you used a high proof alcohol rather than water, you would see a lot more oil output. Hydrosol contains plant material that is dissolvable in water. Oil does not dissolve in water as far as I understand it.

This is just a guess. I have never tried extracting essential oil with a water only distillation. I have done a handful of essential oil distillations in a vacuum still using a high proof neutral spirit and I never had problems getting some oil with my hydrosol.

PS. You should use a very good neutral for this. Something with no smells or flavors. If you don’t make your own neutral or a clean vodka, I recommend you buy a nice triple distilled vodka. There are several old threads on HD where folks shared what they consider the cleanest commercial vodkas. Don’t use everclear or similar products.

Otis
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nzhuhu
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Re: Vacuum distillation...experiment results and silly question.

Post by nzhuhu » Thu Mar 12, 2020 1:44 pm

Thank you Windswept and OtisT,

You might misunderstand Windswept, i am trying to extract oil essential from fruit such as grapefruit but no success, i only collect hydrosol water no oil on top of it.

Thank you OtisT, i really do not want to use any ethanol or chemical even medicine grade. I really hope to get oil from low boiling point of water so it will not harm flavour. I still have not figuring out what is wrong, i wish there is some step by step or any Study of this vacuum distillation technic. Keep looking then.

Best regards.

manu de hanoi
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Re: Vacuum distillation...experiment results and silly question.

Post by manu de hanoi » Fri Nov 27, 2020 7:54 am

what was the volume of water and weight of skins/lemongrass ?

tiramisu
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Re: Vacuum distillation...experiment results and silly question.

Post by tiramisu » Fri Nov 27, 2020 12:52 pm

Ummm, water is a solvent, alcohol is a solvent. There are many solvents. You need to use the solvent suitable for the thing you are trying to extract. Given that you are using vacuum to reduce the heat required it would be seem reasonable to use a more appropriate solvent in order to achieve a more effective extraction. The response that you do not want to use chemicals shows a misunderstanding of the process. Water is as much a chemical as is alcohol. The question is what is most appropriate for oil extraction. You might consider bho or propane extraction as another alternative. It is not clear whether you are trying to achieve separation of turpenes but if so you may want to look to short path or film distillation.

My untrained thought would be to use a soxhlet to extract the oils with minimal alcohol and then use a short path distillation set up and play with separation of the turpenes so that you could create flavor recipes.

JesseMarques
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Re: Vacuum distillation...experiment results and silly question.

Post by JesseMarques » Fri Nov 27, 2020 4:30 pm

actually water is suitable for extracting oil, when you steam distill plant material water vapor can carry molecules with higher BP. The OP seems to know that, as it is wanted to get an hidrosol water with oil on top, but he doesn't have it

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