Making vanilla extract is typically a slow process involving steeping spliced vanilla pods in vodka for months or even years and is considered to age like wine, getting better over time, even once the pods are filtered out after 6-12 months. After watching the first public Harvard lecture on Science and Cooking, in which infusion techniques were discussed, and reading Dave Arnold’s blog post, where he outlines some of the research he did on rapid infusion using pressure, I began to wonder if vanilla extraction could be sped up in a similar way.
The process is pretty simple; put a solvent along with a porous substance into a pressure chamber, increase the pressure in the chamber by adding a gas, leave for a minute or two, then vent the gas rapidly. In the case of vanilla extraction, rather obviously, the solvent is vodka and the porous substance is vanilla pods. As for the pressure chamber and gas, a cream whipper and N20 (also known as laughing gas or nitrous oxide) are used as they are relatively cheap and easy to come by due to being regularly used in the culinary industry and, unlike soda streams and CO2, produce hardly any noticeable effect on the flavour of the final product.
The premise is that the added pressure of the gas forces the solvent to permeate the porous substance where any solutes will be collected and that then venting violently causes the solution, and possibly some of the insolubles, to rapidly rush out of the substance in order to establish an equilibrium. So, for the vanilla extraction the vodka would be permeating the vanilla pods’ cellular membranes, where it takes on the flavours of the vanilla then, during the venting, the vodka solution would be pulling out those flavours and any oils, essentially accelerating the process of osmosis that would normally occur.
So what’s the catch? Well, depending on what you’re infusing, the longer you leave it the greater the infusion but it will also be more bitter and harsh.
To test if this technique would work with vanilla extraction the following was required:
- 0.5L cream whipper
- 8g N2O chargers
- Measuring jug
- Filters or Sieve
- 0.5L Smirnoff vodka – The brand doesn’t matter, most people seem to say use the cheapest, but it does needs to be a minimum of 35% proof (although some sources say 40% proof) if you want to call it vanilla extract due to trading standards.
- Grade ‘B’ Vanilla pods – Sometimes called Extract Grade Vanilla pods. Recipes state a minimum of 8 pods per 250ml of vodka and that you can never have too many. I decided to use 32 pods for my 500ml mix, to make it double strength, since the pods only cost £8 for 100 off of eBay.
- Brown bottles – These are to store the finished product. You can apparently use clear bottles if you store the stuff in a dark place but brown is preferred, especially while pods are still present in the solution, as it minimises the amount of light so reduces the ability for anything nasty to grow in it.
- Something to compare against – You can’t have a food hacking session without a taste test, especially when alcohol is involved!
- Measure out 500ml of vodka and pour into the cream whipper.
- Splice the vanilla pods, scrape out the seeds, and chop up before placing everything into cream whipper.
- Seal the cream whipper and use one of the N2O chargers. You could use an extra charge to get added pressure and presumably get more infusion. I had to use a second one because I had forgotten to vent the gas all in one go so was worried I didn’t have a proper infusion and there was a noticeable taste improvement over what was vented the second time over the first.
- Shake up the whipper a few times and leave for 2 minutes.
- Keeping the whipper upright, to minimise blockages, vent all of the gas in one go. This will be extremely messy so you’ll want to have something to catch all the foam. Even once you think all the gas has been vented be sure to give the handle an extra squeeze or two as it’s possible for the pods to block the valve. You really don’t want to be opening the canister while it’s still pressurised as it’ll spew the contents everywhere.
- With the cream whipper’s gas vented it’s now ok to empty the contents. Depending on whether you plan to use the product as is or to carry on the steeping but in a more traditional way you may want to filter the contents. For this test I did half and half, bottling up some with pod bits and bottling some all filtered, minimal bits.
- Enjoy your tasty vanilla extract (or Kraken tentacles)!
Taste Test, Conclusion and the Future
For the taste test we had a range of vanilla extract products from cheap, midrange, posh, Heather’s own slow steeped homebrew, and even a super cheap “vanilla flavouring” product. Surprisingly the rapid infusion was up there with the posh stuff and slow steeped homebrew but we can’t be certain until we have a bake off!
As for the future, I definitely foresee some fresh ground coffee beans and vodka infusions.