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Jun 08, 2022 View:

Oils in Distillate After Vapor Infusion With Fresh Citrus

We're experimenting with gin and would really love to put citruses in the basket.

We cut up some citruses in half, placed them all in the basket for vapor infusion, used about 90 proof to run a distillation, diluted the hearts (about 170 proof) back down to about 100 proof and let it rest for a couple of days. All was well until we found a layer of oil and the distillate milky, I assume from the oils.

We've done other distillations and vapor infusions with other botanicals without this problem so we're wondering if anyone could help us answer these questions:

1) Why did it happen?
2) How can it be prevented if we insist to do a vapor infusion with citruses? (E.g. Put less citrus? Use lower proof to distill? Faster/slower distillation...?)
3) Any techniques to clear up the currently "oily" distillate?

Any advice would be highly appreciated!


Reply:

Are you making a heads cut to avoid louching of juniper and citrus oils? I sample my gin distillate and dilute 50/50 with RO and don't start my hearts collection until I reach a sample that doesn't louche. Has worked well for me


Reply:On 4/5/2021 at 3:42 AM, tgf said:
Reply:

Did you bring it straight from 170 down to 100? Try stepping the proof down more gradually to prevent flocc/haze, especially when approaching that 100 proof mark or lower. 


Reply:

Also, don't use the entire citrus - rather, just use the zest. We've found using the whole fruit does tend to create more of a problem. 


Reply:

Thank you everyone for your insights!

We did a couple more distillations and got some very interesting findings, perhaps this will help shine a light on what's going on and hopefully we can find out how to stabilize distilling whole citrus fruits via vapor infusion.

Our method largely remained unchanged:
1. We cut up the citruses in half, placed them all in the basket for vapor infusion (no juniper berries for now to eliminate a factor)
2. We used about 90 proof to run a distillation
3. The hearts came out about 170 proof and we diluted it with RO down to 100 proof.


First Batch Trial:
1. Followed @Brewstilla's advice and sampled the heads cut - diluting the distillate with 50/50 RO until no louching was found before collecting hearts.
2. Found that the heads did indeed louch with the added 50/50 RO, but after ten minutes or so, every single louched sample cleared up magically after some stirring and never turned hazy again. On average they were about 100 proof.
3. The hearts, however came out extremely louched after diluting it down to about 100 proof, even after letting it rest for a week.


Second Batch Trial:
1. Followed @kleclerc77's advice and diluted the hearts slowly this time to prevent haze while simultaneously stirring vigorously. The hearts did not louch - amazing.
2. After seeing the successful result of our second batch, we returned back to the louched first batch and gave it some vigorous stirring and magically, the hearts cleared up completely.


Bottling:
After doing the two trial runs above, we decided to bottle the first batch and see what would happened. All was good until about an hour or so after bottling and more than half the bottles began to show up hazy again, while some remained clear. We decided not to do anything just yet and let them sit overnight... and found all the bottles cleared up again by itself the next morning.


Major Questions:
1. Could anyone help draw some conclusions as to why the hearts clear up initially after a long time of vigorous stirring?
2. After the hearts cleared up, why did it louch temporarily after bottling, then cleared up by itself again?


Again, we appreciate any advice and thanks everyone for your input.


Reply:7 hours ago, tgf said:
Reply:

It's oils that have been shocked out of solution and will not re-dissolve. Once they have come out of solution, getting them back in solution is challenging. The best way we have found (without chill filtering, anyway) is as soon as you notice any haze/flocc, bring the proof up with higher proof spirits. Heating and agitating can also help, but maybe not permanently. It's the cold that really does it for us. Because of the extreme cold temps in the winter, we find ourselves needing to bottle at a higher proof. If you're not willing to make that trade-off, chill filtration may be your only foolproof way to avoid haze/flocc.


Reply:

I don't really buy into the shocked thing (at least long term), but this is definitely related to proof, temperature, and oil concentration.  Too low of proof and/or temperature, and too many oils will lead to haze.


Reply:

@Bier Distillery I guess 'louched' out of solution would be a better verb than 'shocked'. I use shock because it can happen very suddenly and I must've heard it described as such at some point.


Reply:

But you can easily reverse absinthe’s (for example) louche simply by adding more absinthe.


Reply:

process wise, consider when proofing how you can increase the contact ratio between the distillate and water. this should help preserve bonds already formed.


Reply:

Bringing this topic back as we've had a couple more months of experience and now have largely solved the issue.

We introduced an agitator during the dilution process and have found that it helped immensely. The increased contact ratio between distillate and water, plus adding the water slowly resulted in a completely haze-free spirit.

We also found that for hazed batches, using the agitator for a couple of minutes helped clear up the haze as well.

Hope that helps.


Reply:

Thanks for posting this @tgif. Am facing many similar issues.

My gin is perfectly clear at 56% ABV (navy strength), but when diluted down to 43% is goes hazy. I'm going to try your slow dilution and agitation regime in the next fews after my gin has rested a little longer at distillation strength (79%). I was wondering however if you could you shed some light on how slowly you're adding water when diluting?

Are you adding it in instalments (i.e. 1L per hour, or day for example) or adding it all in one go, with your agitator running, but just much slower than before?

 


Reply:

In order not to have problems with a "cloudy liquid" you need to focus on the solubility of substances among themselves and in alcohol. You have a problem with essential oils, they have limited water solubility, and they are highly soluble in strong alcohol. With a decrease in the strength of alcohol (the concentration of alcohol in water), it is inevitable to obtain a suspension of an undissolved substance inside the alcohol-water mixture.

The second problem is that this suspension of particles consists of very small particles that you cannot isolate by filtration. Stirring will not eliminate the "fine particles" problem. Gravity from long-term storage will cause the alcohol in the bottle to separate and cause sediment or "smoke in the bottle".

What to do ?

The first option is to carry out distillation under vacuum. This will give a much lower distillation temperature, and all oily (heavy) impurities will leave the output alcohol.

Option two (if you want to work at 78-98 degrees Celsius) you need to think about pre-steaming the citrus fruits, in which you select (isolate and separately remove) the oily components, and do not allow them to be mixed with alcohol on weekends. Volatile (heads) the ethers will remain with you, but it is the oil that is in the skin (lemons, oranges) that will be removed.

Option three - try using an ultrasonic cleaner. Ultrasound allows mixing, in principle, immiscible liquids, due to the production of very small particles inside the alcohol solution. Maybe this will help you, but over time (I wrote above) there may still be sediment or "smoke in a bottle".

P.S. Why do you see "smoke in a bottle" as a problem? There are several "national drinks" in Hungary (a country in Europe) called "Palenca". There it is considered completely normal when "smoke in a bottle" instead of clear alcohol.


Reply:

Reminds me of the old Chem 101 experiment around supersaturated solutions - many did this with dissolving sugar in water at higher temperatures, which resulted in supersaturation at low temps.  Drop in a sugar crystal and poof, out comes all the extra sugar - which will not dissolve again unless reheated.

No idea of these kinds of supersaturated mixtures can occur here.  We say “oils”, but it’s a lot more complex than that (botanical terpenes for example).  

If terpenes and other substances can form supersaturated solutions with ethanol/water - you could see a scenario where slow proofing keeps the solution stable, but if they were to precipitate back out, they won’t redissolve.  The slow proofing theory holds more weight if what we are talking about are meta stable solutions.


Reply:

You cannot trick the Laws of Physics by slowly mixing immiscible liquids.

But there is one interesting question to investigate: can citrus essential oils create hydrates (complex organic compounds with water)? If the answer is yes, then this is a real way to create drinks without smoke in the bottle.

... I see a real working old electric generator that could run on any fuel - from coal dust mixed with water to fuel oil (heavy oil oils) mixed with water. This was only possible due to the fact that the mixture was prepared immediately before being fed into the cylinders, and the mixture was made using an ultrasonic mixer.


Reply:

@Brettski - we're adding it all in one go, just much slower, while running our agitator. We always make sure the distillate clears up before adding in more water.


I had the exact same association as @Silk City Distillers. I suspect the level of our oils/terpenes/whatever they are, are at a concentration where they just needs an extra push (much like heating up a sugary solution), and agitating + slowly adding water is a tried and true method that worked for us with what we distill.

Obviously it might not work for every hazy scenario, but it's worth a shot.