Advanced Kegging Basics

Sponsor my distilling work simply by sharing the artisan workshop of the Bostonapothecary on social media. Copy, Paste, Support!

I used to work in a restaurant with horribly impractical draft and soda systems that functioned like voodoo. I ended up with a lot of regrets about not understanding the systems and how to tune and clean them.  Slowly I realized that if I ever worked in a winery, brewery, or distillery (which I aspire to) I would need a thorough understanding of kegging because they are constantly used for utility purposes.  In beverage production, kegs are used for storing product in oxygen free environments, pressure filtration, topping barrels, and dispensing cleaning chemicals. Poking around the web you find that countless industries use Cornelius style kegs to dispense oils and chemicals).

Everybody seems to use utility kegging except restaurants and bars which strikes me as strange since they use beer kegs. What also strikes me as strange is that restaurant culture has absorbed so much knowledge of craft beer and wine (terroir, how it is made etc…), but never soaked up any winery/brewery wisdom on sanitation or dispensing technique. Very few bars have properly calibrated soda guns yet doing it is extremely simple with a brix cup, syrup separator and flat head screw driver. Bar tonic water might not suck as bad as it does if it were properly calibrated. Near every bar I’ve ever worked in has dirty fridges and unsanitary draft systems. People that clean taps for a living have told me that they won’t drink draft beer from their own clients. When someone changes a keg without sanitizing connectors in a contaminated environment it is like coughing on someone with bubonic plaque. It would never happen in a winery or brewery yet the final market place seems to be oblivious.

Well, I can no longer be ignorant and will make best efforts to set a good example wherever I work. On to the fun stuff…

Cornelius kegs can theoretically (I’m working on proving it) be integrated into a restaurant program in a variety of ways. Used 5 gallon kegs can be acquired at times for free and often as cheaply as $20. New seals and fittings don’t cost too much more and restaurants usually have tons of spare gas tanks around.

For unpredictable, high volume applications kegs can be used to store fresh juices, quickly purged of oxygen in a spatially efficient format. The restaurant I just started at juices its own cranberries and at its best it can taste incredible but it doesn’t seem to get sold at a consistent pace and often oxidizes. Making small batches frequently as a solution can be uneconomical. The cranberry juice, which we make a couple gallons at a time, could simply be put into a keg and purged of oxygen in mere seconds. A cheap plastic “cobra” faucet could dispense it in the walk-in to our squeeze bottles without making a mess like we usually do. I’m really curious to test it, but the same could be done for notoriously perishable lemon and lime juice. Lemons and limes oxidize incredibly fast and can turn to “pine-sol” over night. Erratically high volume bars could potentially juice for a couple days if they could store their juice oxygen free. Purging as you add every quart could possibly prevent enough oxygen absorption that you could safely keep on hand 5 gallons of lemon juice say for a massive event taking place the next day (it remains to be tested [finally tested!]). In tight quarters, a pastry department could dispense a beautifully un-oxidized fruit soup at large and unpredictable volumes (kegging will only prevent oxidation, not eventual fermentation from wild yeasts).

EDITED TO ADD: KEGGING WILL NOT PREVENT ENZYMATIC BITTERING WHICH IS THE SECOND SCOURGE OF CITRUS JUICES. [ACTUALLY IT IS OFTEN CHARMING]

The next application is pressure filtration which has been developed for home brewing. Many restaurants now sell massive volumes of house made liqueurs and infused spirits that can benefit from “polishing”. Buchner funnels are small and expensive rivaling the price of a Cornelius keg filter setup. Chefs could possibly also use filtration for delicate waters and consommes. What needs to be tested is how well the filters can handle pectin which often destroys a wine filter by clogging it. [NOW A DAYS YOU CAN ALSO USE PECTIC ENZYZMES!]

The next thing that can be done with a Cornelius keg is filling it with syrup or concentrate and integrating it into a “wonder bar” soda gun instead of a typical bag in the box. The syrup can either go to a free water or a free soda water channel. Unfortunately the kegs contents have to be either blended with water or soda water at a ratio near 5 to 1. I don’t even think you can get as low as 2 to 1 because the screw that adjust the syrup will leak and potentially pop out creating a serious mess so you could never have a margarita dispensed from a typical soda gun. You would need a separate rig, which does exist, for the night club industry.

The most elaborate and impressive thing a Cornelius keg can do is force carbonate which dissolves C02 into a liquid which can either be dispensed on draft or counter pressure bottle filled into a beer or champagne bottle and capped. The possibilities of the technology are mind blowing but its easier said than done and you need a few hundred dollars worth of specialty parts.

Besides being clean, pressurized draft systems have to be “balanced” which means that what you serve has to be able to come out of the tap without foaming to death. The right pressure and spout for the right beer and most importantly in between, the right hose. The walls of the hose resist the liquid passing over it effecting whether CO2 comes out of solution or not. The resistance is relative to the material and the length of the hose and should be slightly less than your PSI. (I’m regurgitating this, I really haven’t figured it all out). Soda and force carbonated wine exist in pressures far beyond beer and I’m not sure if common home brew equipment scales up high enough.

EDITED TO ADD: EVERY PROSECCO I’VE EVER HAD ON TAP HAS SUCKED AND HAS BEEN BARELY CARBONATED.  UNLESS YOU TRULY UNDERSTAND WHAT YOU ARE DOING DO NOT TRY IT AND WASTE OUR PRECIOUS DINING DOLLARS.

Ginger beer exists at beer pressures and I’m sure can be bottled easily enough, the tart and brut hibiscus soda of my dreams exists at champagne pressures and I’m sure is a trick to get into the bottle. Something else that is theoretically possible is to do something with distressed wines on the market. Many distributors have white wine that is too old. Some whites become frail and sickly (universally dead) while others just become so nutty they are obnoxious and one dimensional after they have lost their fruit contrast; desirable flavors in a sparkler. Trade the fruit for bubbles and you have got something interesting enough to drink. Let it sit under pressure long enough and I’m sure the bubbles will be of champagne quality (what you hear about champagne method bubbles being superior is likely BS). I’ve seen some great wines out there like vintage 2000 Grechetto sold for $2/750ml. The wine was liquid hazelnuts and would be a shame to see it go down the drain (60 cases).

These are all just ideas I’m slowly going to develop and test. I’d love to hear of any one else’s experiences with the technology.

Follow @b_apothecary

14 thoughts on “Advanced Kegging Basics

  1. As a long-time homebrewer I’ve been playing with corny kegs for many years and agree–they’re wonderful things and it sounds like they can be applied to many restaurant applications. Two notes of caution regarding storing cranberry juice in a keg: First of all, liquid stored in a keg with CO2 will start absorbing the gas and so will become carbonated. That may not be appropriate for juice, so perhaps another gas (nitrogen?) might be a better option. Colder liquid actually absorbs CO2 faster and more readily than warmer liquids, so this is an important consideration. Second issue is that fresh juice WILL begin to ferment relatively quickly. Fermentation can be retarded using refrigeration, but the yeast will continue to work, and eventually pressure will build up. The end result, if you’re not careful, will be an expoding keg. This would, in a restaurant enviornment, probably mean that someone left a keg of fresh juice in some dark, forgotten corner of the walk in, and I hope in most establishments there are few dark and forgotten corners but it could certainly happen. So please don’t let it… I suspect it would not be a pretty thing to witness.

  2. hi adam. i think you can avoid the carbonation of the juice by purging the keg of oxygen but leaving minimal, near atmospheric pressure. there would be very little absorption by the liquid to return to equilibrium. your caution about fermenting cranberry juice is really interesting. i’m not sure exactly what happens. is say 2 gallons of juice with a potential alcohol of maybe 4% enough to explode? right now the juice is in the fridge intensely wrapped in plastic wrap and never even pushes the wrap into a dome. i wonder though if you could change the safety valve to something rated for much less pressure to remain totally on the safe side.

  3. Neat & inspiring musings as always Adam! Incidentally, in response to your wistful-sounding comment on the “Hibiscus soda of your dreams”; from an article just finished & about to hit my blog:

    Jamaica soda
    3¼ Cups: Water
    ¾ Cup: dried Hibiscus flowers
    ¼ Cup: raw Sugar
    2½ oz. light Agave nectar
    1½ oz. Cinnamon syrup
    Bring the Water & Hibiscus to a boil in a non-reactive saucepan before stirring in the Sugar. Reduce heat slightly & simmer for 6-7 minutes, stirring occasionally. Remove from heat, stir in syrups (Cinnamon optional, sub in more Agave), cover & cool completely to room temperature (3~4 hours). Fine-strain by preferred method (cheesecloth, chinois, &c), pressing on solids to extract as much liquid as possible.
    Pour into a soda siphon (should fill a standard iSi to an optimal pressure point). Carbonate, shake & chill according to your model’s instructions.

    Way better than Jarritos’ super-sickly-sweet “Jamaica” brew; pleasantly-tart as is (& should be), but feel free to fiddle with the sweeteners to get your dream product.

    Cheers!

  4. That is, Stephen, not Adam.

  5. Just realized I made a mistake – I had copied my recipe for still Jamaica down from my notes, rather than the soda. If the above goes into a siphon it will likely make a teensy bit of soda and a lot of foam. The actual recipe hit my site yesterday, but includes bit of citric acid and Lime zest to compensate – 3/4 Tsp of each I believe.

    Sorry & Enjoy!

  6. i used to a play with an isi syphon that was glass wrapped in a metal mesh. a pretty cool model. what i found is that the best sodas came from not dispensing them through the siphon head but merely by unscrewing the top and pouring them like a two liter. very little foam. that is why i’m trying to make a rig to use standard champagne bottles.

  7. Corny kegs rule. As for fermentation inside, I’m unaware of any kegs sold without safety valves. Certainly I wouldn’t recommend buying any without that critical feature. So I wouldn’t worry about exploding kegs, although obviously you don’t want your juices fermenting anyway. Unless you do…in which case, use a carboy ;-)

  8. Hi there

    We are a cold press juice business and wanting to key our juice to pour from a bar tap.

    Only issue is that the juice separates when left sitting for a few hours. any ideas how we can stop this from happening?

  9. Hi Will, sadly you are in really tricky territory. Any thing you add would detract from the naturalness of the juice. Constant agitation may be a solution but it is very challenging to adapt an ordinary keg for a magnetic stirrer or something like that. If you agitate and draw only from the very bottom you still may miss a lot that is at the top.

  10. Will Ross
    You can modify a keg to use a long liquid or beverage out dip tube instead of the short gas dip tube. With each pour the incoming gas disrupts the settled suspension, mixing it up. You’ll want to use a disconnect with an integrated check valve, so the liquid can’t get into the gas line if there is more pressure in the keg than on the line.
    I’m sure you already were, but recommend using straight nitrogen for juice, and using it to purge oxygen from the product and the keg.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

search previous next tag category expand menu location phone mail time cart zoom edit close