Mike McDonald
When I was a kid, my dad used to take me to work (Lawrence Berkeley National Lab) and let me “help” him with his experiments, which often meant “filling a dewar with liquid nitrogen (LN) and carrying it back to an experiment.” Mind you, I was probably about five when this started. Definitely not safe for work…
Every now and then, if I remembered, I’d bring a thermos and some tin foil (never seal the top of a container of LN) and ask to fill it with LN to bring home to freeze flowers and watch them shatter, make perfectly smooth ice cream, or otherwise “do science” with this strange liquid.
While my drive to do science hasn’t changed much in the two decades since I filled dewars in the Berkeley hills, my access to LN has, so when I came across Dave Arnold’s “nitro-muddling” (generally “cryo-muddling”) in Liquid Intelligence (pg 165), I knew I had to find a more accessible way to try it.
Why cryo-muddle in the first place?
Like most millennials (and CA natives), I love avocados, but only fresh avocados, not the “avocado that’s been sitting in the fridge for a day or two” browned, rubbery tasting avocado. This browning and oxidation (and off taste) comes from polyphenol oxidase (PPO), which increases when the avocado is cut open.
Turns out, when you muddle herbs, the same enzyme is released and causes them to brown (far faster than the avocado you left in the fridge overnight), resulting in an boring color and off flavor beverage. Wouldn’t it be great if we could stop the reaction and keep the vibrant color and pure herb flavor?
Turns out that alcohol and vitamin C are able to neutralize PPO (hence why guacamole, with lime, browns slower than a plain avocado, and why tequila infused guac presumably brows slower than both…), but it’s not easy to get those into the muddled herb quickly enough, unless the herbs are finely powdered. Which brings us back to freezing flowers with LN and shattering them…
Cryo-muddling allows you to freeze an herb (or a flower), powder it, and then introduce both alcohol and vitamin C to stop the oxidization, ensuring that you can capture the unoxidized flavor of the herb as well as the neon color.
Why dry ice?
Unfortunately, LN isn’t easy to come by: you need to go to a specialty supplier (e.g. Airgas or your local welding supply shop), bring a dewar (you can’t just show up with a thermos bottle), and beg them to sell you a much smaller volume than they normally do. Fortunately, dry ice is cheaper, easier to transport, and works almost as well as LN.
You can buy dry ice at many grocery stores (I found some at my local King Soopers, though make sure to call ahead as not all stores have it), and it costs roughly $1/lb. A pound is far more than what you’ll need for a night of drinks at home. When you pick it up, make sure to bring a cooler (I use this, which serves dual duty as my clear ice container).
Turns out using dry ice (what I’m coining “dryo-muddling”) works just as well, with far less hassle, provided you follow these steps.
Dryo-muddling technique
A quick safety note before we get started: make sure that you never touch dry ice, as it will very quickly freeze things it comes in contact with! Wear gloves and eye protection, handle with tongs, etc., and make 100% sure you don’t ingest it!
Roughly speaking, the steps in dryo muddling are as follows:
- Put herbs in a metal shaker tin
- Add a chunk of dry ice on top of the herbs
- “Muddle” to a fine powder
- Add high proof liquor to other side of the shaker tin
- Slowly pour herb/dry ice mixture into the liquor
- Add the rest of the cocktail, add ice, shake/stir as appropriate
- Strain through two fine mesh sieves
In more detail, and with pictures:
Add 4-6g of herbs to the bottom of stainless steel shaker tins (I use this).
Add your dry ice to the tin and pound the chunk into a lot of smaller chunks covering your herbs, then grind the herbs into a fine powder. My muddler of choice is the “Bad Ass Muddler”.
If you did everything right, you’ll get something that looks like this:
Add the dry ice and powdered herb into the other shaker tin where you’ve put your spirit(s), stirring it to ensure it gets mixed and no clumps form and freeze. I always imagine myself buying a hot plate and magnetic stir bar for this, but that’s maybe overkill. The goal here is to mix the herbs into the alcohol and prevent the PPO oxidization while also sublimating all the dry ice off. When the drink stops “smoking” (no more dry ice left), you’re good to go.
You’re probably fine adding the whole cocktail to the other shaker (alcohol, acid, and sugar), since the freezing point is still high enough, but I usually stick with the lowest freezing point (highest ABV) just to be sure.
Note: the first time I made this, I tossed ice on top of my herb/dry ice powder and proceeded to make the drink as usual. Don’t do this! As the dry ice sublimated it repeatedly broke the seal on my shaker tin (exploding Mojito all over me), and when I finally opened the tins to see my cocktail, it was entirely frozen and there was basically no cocktail left!
Given this, I was concerned that the addition of dry ice was lowering the temperature of the liquid too much and reducing the dilution of the cocktail. I measured the temperature of the liquid before and after the addition of the herb/dry ice mixture, and it went from ~15C to ~10C, which seemed like a not terribly significant difference, though I likely need to try some other variations.
After you’ve made the cocktail, you’ll want to double strain it through a tea strainer or other fine mesh sieve (I use this). This will get out most of the little herb pieces, as well as any remaining dry ice pieces (though if you follow the procedure from above and wait until it’s all sublimated, you shouldn’t worry about this).
As you can see from my finished version, I only strained it through one strainer, hence why there are still some mint chunks.
The above cocktail is a fairly standard Mojito, though served up instead of as the more traditional highball:
- 60 ml white rum
- 22.5 ml fresh squeezed and strained lime juice
- 22.5 ml simple syrup
- 6 g mint leaves, cryo muddled into a fine powder
- (Optional) club soda, if you want to serve it on the rocks
And if you want to see all the steps, it’s on my Instagram!
More cocktail madness coming up
If you’re sick of the cocktail related content, sorry, I’ve got at least one more post in me. In Between the Sheets I played around with carbonating cocktails, but along the way I made nitro cocktails (since all I had was an iSi whipper). They were fine, but I felt like an actual nitro setup would be better, and would allow me to try other things, like nitro cold brew tea. The tank and regulator will be here Friday, so I should be able to experiment over the weekend and report back!