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The weird science of ethanol-water-sugar solutions - cooking some limoncello

I really wanted to do some house-crafted limoncello today, for our Italian restaurant. And instead of zesting lemons, I had the idea of using whole fruits.

Yes - usually zests working better - because there is far more surface. However my good friend, the sous-vide immersion circulator helped to cut the time in a fraction of traditional limoncello.

The normal procedure of limoncello is:

  • Zest [cleaned] lemons
  • Add them into alcohol
    • Traditionally high proof grain alcohol is used - however using vodka is just fine, if you are regarding the difference in ABV.
    • Obviously in Italy high proof booze is used, as it is in production far cheaper than the refined product 'vodka'.
  • Wait for several weeks [depending on the size of the zest pieces].
  • Strain and add sugar syrup [depending on the original occurring alcohol strength and the target strength].
  • Bottle and label.
Now - I want to do this procedure as well - with two major differences:
  • I want to use whole lemons - due to following reason
  • I want to "hang" the lemons above the vodka - and don't want to suspend it into the liquor.
This is one procedure, I have seen in Not only it looks cool to use the whole fruits, it also results into a smoother result. And off course, every guest will ask "what you have there". Obviously things like that just increase the coolness of a venue.

The main problem is, that I need NOW limoncello.

There are several ways to fast-track infusions. You can cut the "botanical" into very small pieces - the more surface the faster the extraction [which is possible to practice in the extreme - pulverizing the botanical and then after infusing the liquor, filtering it out [or clarifying it].

Second: Nitro-cavitation. Add the botanical and the liquor into a siphon and charging it with N2O.
Honestly - this is not mine. I so wanted that it works - but the results of my tests weren't that great.

Third: Vacuum-cavitation. Yes - you can vacuum your liquor with the botanical inside - several times. You just have to make sure, that you don't pull a too strong vacuum and all alcohol boils over into your chamber vacuum sealer [which you definitely need for it].

Fourth: Use heat. The problem is, that if you would use your stove top, that over some time quite a lot of alcohol would evaporate. Less than ideal! Also - too high heat, would denature the flavors.
The solution is a immersion circulator [or any other "sous vide" equipment you do own].
As it is sealed in a plastic pouch, alcohol cannot evaporate - and the controlled temperature bath ensures, that it does not heat too much.

Now this is what I did:
  • Wash lemons with ice water.
  • Add them to a vacuum bag, add sugar and vodka.
  • Seal the bag.
  • Let them "swim" for about 3 hours at 55C.
  • Refrigerate the pouch [as we are all children in hospitality we used the blast chiller... however an ice bath would be perfectly fine :) ]
  • Open the bag, strain the lemons out of it.
  • Add some water in the limoncello.
  • Pour into a decorative bottle.
  • Label...
It sounds a bit complicated, but really it isn't.
I used Sous Vide Supreme recipes - but found after tasting the limoncello, that they totally miscalculated the sugar - it needed some more. Also, the recipe is calling for far too much water - they mentioned a 1:1 ratio of vodka to water - and you would end up with about 20% abv [or lower], however proper limoncello has about 28-32% abv.

I roughly calculated that I needed to add about 300 ml of water to the mix [not about 1l!].
Now here was the weird thing, which lead to the unusual header: I added 1000 g water to 290 g sugar originally and added the lemons [which are quite solid]. After straining the liquid I ended up with 900 ml of vodka. What? Yes - angel share [or should I call it Poseidon share - cause everything stayed submerged in water?]. I tasted the lemons afterwards, but they were not saturated with alcohol. I can only think, that the sugar resulted in a far denser liquid?!? I don't even want to get too deep into it - as Chemistry wasn't my best discipline...

Anyway - all resulted into a pleasant limoncello. Not the best I could imagine [I blame it to the lemons, which were far from superior] - however nice, fresh and clean tasting.

I will report in a few months, how the other method is working - looking forward to try more lemon flavored hooch!



  1. thank for your helpful infomation. I have used foodsaver 4840 and I'm really satisfied with this product. There are a lot of helpful functions. You should buy one as soon as possible if you can.

    1. Hi Annie, thanks for the comment. I am using a foodsaver at home. It was quite tough to get it to Dubai - because at the time I bought it, it wasn't available in the Middle East [I actually got it shipped from the US and had to buy a power converter]. Nowadays, you can buy one...

      I am especially a fan of the chamber vacuum sealers on work. They pull as much vacuum, that the liquid is starting to cook at room temperature. The vacuum cavitation is also much stronger, due to the very low pressure. Unfortunately they are not really an option for at home, because they cost thousands of dollars!


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