Archive for May, 2012

Rapid Infusion Coffee Vodka

As a continuation of the attempts at rapid infusion, this experiment tries to mimic the one Dave Arnold demonstrated in the first public Harvard lecture on Science and Cooking in which he created coffee vodka.

Coffee vodka

The Theory and Technique

The most common way for infusing coffee is by brewing it in hot water however, if you’re wanting to drink the coffee cold, letting it cool will result in an overwhelming astringent flavour. This is due the chlorogenic acid in the coffee forming quinic acid as it cools. In order to reduce this apparent acidity the coffee needs to be brewed in a way that does not involve heat. Cold brewing coffee is easy enough but it takes considerably longer (sometimes 12-24 hours) so, just as with the vanilla extract experiment, this aims to drastically reduce that time to a few minutes. As this builds upon the vanilla extract experiment the theory and technique are the same so no need to repeat that here however it is probably worth mentioning that the N2O will add a slight sweetness to the coffee (whereas using CO2 would add a metallic-like tang).

The Experiment

The ingredients

  • 0.5L cream whipper
  • 8g N2O chargers
  • Coffee grinder
  • Measuring jug
  • Coffee filters
  • 0.5L Smirnoff vodka
  • 500g Coffee beans
  • Something to compare against – Since the coffee vodka is made to go with cream and milk the comparator for this experiment would be a White Russian which is a mixture of Kahula, cream, full fat milk and vodka.

The Process

  1. Grind 500g of fresh coffee beans as fine as possible and add into the cream whipper.GrindingFresh coffee grounds
  2. Add 0.5L of vodka to cream whipper.
  3. Seal up the whipper, add charges, and give it all a bit of a shake.
  4. Leave to sit for 2 minutes.
  5. 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 the grounds may have blocked the valve. You really don’t want to be opening the canister while it’s still pressurised as it’ll spew the contents everywhere.
  6. With the canister vented it’s time to filter the coffee grounds from our vodka solution using the filters. You’ll probably want to filter the mixture at least twice.Filtering
  7. Enjoy!

Taste Test, Conclusion and the Future

For the taste test we added some full fat milk and cream to 25ml of coffee vodka and mixed some White Russians (25ml Kahula, 25ml vodka, milk). The White Russian was inherently a lot sweeter due to the Kahula while the coffee vodka was extremely bitter and intense. This is likely due to having used expresso beans so for future testing a less intense bean would be better. Better results would probably be achieved if we ground the beans finer and did an additional filter process.

(Photographs courtesy of Heather Sullivan)

Making Movies

I’ve been wanting to try make some simple documentation videos for a while now and as I’m generally a Mac user I’ve been attempting to learn how to use the basic features of iMovie. Luckily enough, I recently managed to capture Tom Wyatt and Thomas Greer showing off their Nerf gun project so used that as the basis for my first video as it seemed like a nice easy starting point.

I was using a Samsung Galaxy Nexus so it’s not the best quality video out there and it’s a bit shaky despite my attempts at using post processing video stabilisation but I think it’s not too bad for a first attempt at using the software and making videos. It’s definitely worth noting though that if you attempt to use iMovie’s video stabilisation on a mp4 format video file it will error during the last stages of the process so you have to first convert the file to another format if you want to make use of that feature, which is a rather annoying and a major time waste (especially as the error doesn’t tell you why it didn’t work and you end up having to Google the problem).

After that I turned to something I thought would be a little harder, turning some older pictures I had taken using a GoPro HD Hero2 into a time lapse video. The GoPro comes with a configurable mode for taking time lapse shots and I had used this set on an interval of 30 seconds to capture Heather constructing her Ice Tube Clock. It was a bit fiddly getting the resulting pictures to work properly in iMovie since it defaults to crop and transition over any used photograph rather than just simply display them and the software seemed a bit flaky when telling it to “Fit” (what you have to set in order to prevent the croppy-transition-ness) on a large selection of pictures but I got it to work in the end. In all, the build took about 3 hours and the resulting video was roughly 1 minute 10 seconds long.

There are probably better programs out there than iMovie but, for now, it does what I want so the learning continues…

Rapid Vanilla Extract

Vanilla Extract

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 Technique

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 Theory

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.

The Experiment

To test if this technique would work with vanilla extraction the following was required:

The ingredients and equipment

  • 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!

The Process

  1. Measure out 500ml of vodka and pour into the cream whipper.
  2. Splice the vanilla pods, scrape out the seeds, and chop up before placing everything into cream whipper.
    Chopping and splicing the vanilla pods
  3. 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.
  4. Shake up the whipper a few times and leave for 2 minutes.
  5. 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.
  6. 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.
    To filter or not to filter?
  7. Enjoy your tasty vanilla extract (or Kraken tentacles)!
    Vanilla extract!

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.

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Shinkutanku; Japanese for “Think Tank”. A very infrequently updated blog by your average code-monkey cum photographer.

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Twitter: @CiaranEaton