Corny cocktail keg advice

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fahey32

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Hey guys, been a while since I've been on here sadly due to work and study and the lack of available time for brewing :(. However working in cocktail bars I have recently gotten involved in kegged cocktails which have been a hit with punters and staff (who have an understandable aversion to mojito's). And It has been a great excuse to dust off the old kegging and brewing equipment, yay!

To make my Mojito's I have been using the 'rapid infusion' technique with an iSi creamer siphon to force the alcohol under pressure into the pores of the mint leaves then quickly releasing the pressure after a few mins to allow nucleation to extract the menthol from the leaves without the chlorophyl, in order to avoid bitterness and greening (there's a great article here: http://www.cookingissues.com/2010/08/11/infusion-profusion-game-changing-fast-%E2%80%98n-cheap-technique/ ). It worked a treat! So much so that the full keg was finished in 4 hours ~ 120 mojito's. Problem is that the siphon only has a capacity of 500ml and so I need to go through the whole process 36 times which takes hours. To save time I was thinking about adding all the ingredients to the keg and charging the entire keg in one go then quickly releasing the pressure. CO2 bubbles are too large to nucleate and form on the inside of the pores and NO is expensive and difficult to acquire in bulk (understandably). Firstly, would I be right in assuming that I can probably get the same effect with straight Nitrogen?

From a bit of math I calculated the pressure inside the foamer to be roughly 6 atm (or ~ 609 Kpa, 88 PSI), Does anyone know or have an idea if this sounds correct? I've read that Corny kegs are rated to 120 PSI so it should be safe and doable yes? after the whole keg explosion incident in NSW I'm a little dubious about the whole process so I'll probably bury the keg in sand while attempting this just to be on the safe side.

Finally, To quick release the pressure I plan on removing the bleed valve at the top and fitting a ball valve. I wanted to get your opinions before I undertake this as it could be a rather costly failure and I've noticed that my kegs have much thinner walls than the siphon. Any advice or confirmation would be appreciated.
 
Not sure if you'll get the same results with nitrogen. Nitrous is soluble @ 1.5g/L while Nitrogen is only 20mg/L. We keg our wine using nitrogen as it's solubility is so low.
 
If I were to use nitrous creamer bulbs instead where would I be able to find an adapter for the corny keg system? I've seen people talking about them but I can't seem to track one down.
 
Not 100% as i dont own one but the portable keg chargers should work with nitrous bulbs.
 
Sure seems as if straight nitrogen is the proper way anyhow. N2O is probably just used as it is more easily found in a kitchen environment.

You can release the pressure quickly enough with the pressure release valve in the top of the keg. I haven't seen a corny keg rated for less than 120 psi. The release valve will let go first anyhow, assuming it is in good condition.

I would try a test run with compressed air - air is mostly Nitrogen anyhow. Sure, you run the risk of oxidation, but in the end if it works, it is a hell of a lot cheaper and easier than screwing around with expensive gas cylinders. No reason is has to be a big batch for a test run either, doesn't matter is the keg is mostly empty.
 
I have modded one of those small keg chargers to accept 8g co2 cartridges (rather than the usual 16g ones) so a nitrous cartridge should not present an issue i would have thought, you shortern the space inside the holder by the right amount - i did it with some dowel
 
Problem with the keg chargers is they all seem to take 'screw in' CO2 bulbs which don't seem to exist for NO unless there are threadless bulb keg chargers somewhere because that would work. I have an iSi whipping siphon so if I can potentially find a bare S30 valve somewhere I could use the bulb cover from the siphon (assuming the outside thread is the same size).

Oxidation is a rather large issue here as the chlorophyll from the mint can very quickly oxidize and go brown which is not a very appetising and forced oxidation/cavitation may accelerate this further. Looking at the cell disruption article, the working pressure is 2200 PSI! More than 20 times the pressures we are talking about. I'm assuming this is to reach an acceptable solubility of nitrogen in water for enough violent cavitation to form from depressurising. But in saying that 'the bends' in diving relies on a similar principal and can occur within a relatively sudden change of as much as 1 atmosphere (if I remember correctly) so there may be enough solubility for this to occur it just might require charging it and depressurising it more than once to release enough menthol. This could use up a fair amount of N2 though so it may be cheaper to use NO at the end of the day.
 
Have a look at the paintball co2 quick change cartridge holders. Could be of some use?
 
fahey32 said:
Problem with the keg chargers is they all seem to take 'screw in' CO2 bulbs which don't seem to exist for NO unless there are threadless bulb keg chargers somewhere because that would work. I have an iSi whipping siphon so if I can potentially find a bare S30 valve somewhere I could use the bulb cover from the siphon (assuming the outside thread is the same size).
the one i have will take ether but i prefer the threaded.
 
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