Fresh citrus juice has become somewhat of a fetish in our industry, for reasons that are understandable. We are, as a community, still suffering from PTSD caused by too many cloying, artificially-flavored “martinis” served for too many decades.

Fresh citrus juice, however, is very economically unfriendly. It’s labor-intense. There’s nothing worse than staring down a line of customers and having to stop to juice 5 limes. And citrus ain’t cheap, especially at certain times of the year when the cost of fruit triples and their yield halves. There are times when the citrus in the drink costs more than the liquor.

On the other hand, anyone who has ever tried day-old lime juice (or worse, the pasteurized stuff) can tell you it’s just not the same. It doesn’t have that same brightness.

In a perfect world, citrus juice would last weeks. Then you could juice it all at once. (This has the side benefit of making cheap Chinese Zumex knockoffs like the one I got economical. More on that in a second.) If you had extra, you could use it tomorrow. Or the next day. You’d never run out of what you made pre-shift, and never pour any down the drain. You’d also be using all-natural ingredients and techniques, because you don’t want to serve anything you wouldn’t want to eat.

Well, I’ve got a solution.

To understand you have to go back to the whole citrus. The whole fruit contains a number of different things. It’s mostly water. It contains all sorts of other chemicals, trapped in its vesicles, the most flavorful of which are citric acid in lemons, and in limes citric and malic acids, with a touch of succinic. But the most flavorful component of all is the oil trapped in the peels.

When you squeeze a lime, you’re not seeing it but you’re also expressing that beautiful oil into the juice. You probably think that because it’s a tiny, tiny fraction of the juice that it doesn’t make much difference. Go ahead and buy yourself some lime essential oil and squeeze one tiny drop onto your tongue if you want to see just how wrong that is. In fact, even one drop of lemon essential oil added to an entire drink can make it taste like Pledge.

The essential oil is the most distinctive flavor ingredient in citrus juice. Want to try it out more diluted? Get a La Croix or a similar, 0 calorie flavored carbonated water. They’re basically just essential oil flavors emulsified into carbonated water. Lime La Croix has no actual lime juice in it, just lime essential oil.

Essential oils have one problem: they are very sensitive to pH and citrus juice is very acidic. They both have a pH as low as 2. That’s not a problem when they’re sitting in oil sacs in the outside layer of the citrus (called the flavedo) and separated from the juicy vesicles by the pith (the albedo). But when you squeeze citrus and combine the oils that are normally separated from the juice, breakdown begins immediately.

Modernist Cuisine offers two solutions for this problem. The first is to simply dope older citrus juice with fresh stuff shortly before serving time. This is what I do during camper season. If I have a gallon of lime juice leftover from the previous weekend (usually out of 5 gallons I started with) I’ll just add it to the next batch. Easy peasy. I just juice a little less and pour it all into the keg.

In a bar setting this might be less ideal. So another option is to emulsify some lime essential oil (you can buy the food-grade stuff pretty easily online) with gum Arabic and just add it in. I’ve been playing with the idea of diluting it down enough to put it in an atomizer and spray over the drink or onto the glass before the drink goes in, but I haven’t had a chance to test it yet.

Another undesirable reaction is occurring at the same time: oxidation. This is pretty easy to stop, you just put the juice in a keg and purge with nitrogen. Fill the keg with nitrogen, then purge, and repeat a couple times to try to get as much oxygen as you can out. Then shake the crap out of it to try to knock as much dissolved oxygen as you can out of suspension, purge, and repeat a couple times. It takes a minute or two, but you can get it to a pretty low dissolved oxygen level. (Any of my readers want to loan me a DO meter?)

By doing both of these, you get lime juice that lasts. I’ve used week-old lime juice side by side with same day stuff and in a cocktail you can’t tell the difference. My overall process is as follows now.

1. Juice limes no more than a day before serving. If you’re doing regular bar service, Friday shortly before you open would be a great time and probably get you through Saturday.

I found myself juicing at least one case of citrus every Friday, and sometimes more like 5 depending on my weekend. Being a solo entrepreneur, that kind of time commitment with the old hand press just wasn’t going to scale. So I got myself a knockoff Chinese version of a Zumex.

It works great. It has a couple downsides, in that it needs a few modifications I plan to make over the winter. The tray that holds the juice is really hard to clean if you don’t unscrew it every time, so I bought thumbscrews to make that easy. It still needs me to make it a gasket. The thing leaks juice everywhere, and because it’s sized for oranges, it’s probably getting less juice out of smaller citrus than you’d get with a Zumex kitted with the lemon/lime adapters. But, it does a whole case of limes in like 10 minutes with no arm strain, so it cuts my time down enough to recoup that cost.

Cleanup is about 10 minutes, so you don’t save much time if you’re only juicing a few dozen limes. Which is yet another reason to use my method: juicing once every few days for a small bar saves you the daily chore.

Of course you must fine-strain what comes out or else you’ll risk jamming your kegs or faucets. (I find the faucets usually jam due to particulate matter, but the kegs due to sludgy things like honey that wasn’t dissolved well-enough.)

2. Put juice in nitrogen-purged keg, of course keeping refrigerated at all times.

3. Pour lime juice into bottles with pour spouts for service. (Anything left does not go back in at the end but gets saved for cordial down the line.) For big events, I have a dedicated tap for lime juice in my camper, allowing me to keep it under nitrogen the whole time.

4. Repeat next week by adding leftovers to fresh juice. I find at least 50% fresh juice makes it taste great.

After a few weeks of this I’ll usually have a weekend where I run out and start over, but if I don’t, I’ll take the little that’s left and add it to the keg of cordial stuff. (And yes, that’s why I do a preponderance of gimlets later in the season. I’m currently sitting on about 6 gallons of cordial!)

So there’s my process. It’s extremely time-efficient, keeps lime juice from being wasted (I have damn-near zero waste) with minimal effort, and thus saves on both ingredient and labor costs. And with no reduction in quality. It’s really pretty simple, and the investment in equipment (the juice and kegging stuff probably adds up to over $1,000) pays for itself very, very quickly. I am sure it has saved me over 100 hours and a few hundred dollars in limes just this season. If I even valued my time at minimum wage (and of course, it’s way more) it would have still broken even.