A few weeks back, Cooking Issues posted a pretty rad post about infusing liquids with flavors using NO2 cartridges and a cream whipper. Because science is awesome, I wanted to try doing this. I’m starting in on the Matsutake dish from the book, and one of the components of it is Rosemary Gel.
It’s typical to start making an herb-flavored gel by making a ‘tea’ of the herbs; boil some water, then pour the water over the herbs (you usually need a lot of herbs), then let it steep. The length of steeping time varies from herb to herb; the danger is similar to that of making coffee: the desirable flavors are released before the bitter ones, so what we seek is to release as many of the swanky flavors as we can, then stop the infusion before too many of the bitter ones make it into the infusion.
My mom likes to drink tea in the following way: fill a mug with water, add a tea bag, microwave for 2 minutes, drink some of the tea over the course of 20 minutes (never removing the bag), get distracted, forget the tea, find it 3 hours later, re-microwave it, add more sugar, finish tea, add more water (never removing the bag), repeat. It wasn’t until I moved to NZ that I learn to TAKE THE TEA BAG OUT of the water if I didn’t want to be drinking straight throat-burn. In the world of Alinea, we want to circumvent behaviors like this.
The Cooking Issues post largely revolves around infusing alcohol. I didn’t really understand why until after I’d tried this, but there’s a reason (WAIT FOR IT). But I figured if it works for vodka, it should easily work for water, so I wanted to try it.
The first thing I did was make the original Alinea recipe: boil some water, pour it over 2 rosemary sprigs, let it sit for an hour, strain. I tasted the result to get an idea of what I needed to be shooting for. When I lifted the lid off the covered steeping bowl, the steam was extremely heady and ‘minty’ almost. I get the sense that there are a lot of oils released into the vapor during this process, in addition to the regular rosemary flavors. Also, I used whole sprigs, so the wooded ‘stems’ of the rosemary infused as well. The resulting tea was pretty strong and very aromatic, and the rosemary sprigs at the end of the process were very brown and lifeless.
To try to replicate this flavor with the nitrous approach was like flying blind; I didn’t really know where to start. My canister can only hold maybe a few cups of water, so I opted to half the alinea recipe water amount, thinking if stuff worked I’d just do it twice. I started with one sprig rosemary, pulling off the leaves and adding only them to the canister. I pressurized the canister, swirled gently for 30 secs, and then let it steep for 30 more seconds, just as the Cooking Issues blog mentioned. I suspected up front that this was too short a time; usually Alinea teas undergo very very short (less than 30 seconds) steeping times with hot water, so the fact that it called for me letting the rosemary steep for an hour led me to suspect this was because rosemary is tough and takes time to give up its flavors. I discharged the canister and strained the water.
The result was notably more subtle than the Alinea tea. It was also ‘lighter’, way less heady. So I poured the water back into the canister, added 4 whole sprigs of rosemary (thinking the stems played an important role), and charged the canister again. This time I swirled it for 45 seconds and let it sit for a minute before discharging it. The result this time was definitely stronger, but still ‘cleaner’ and less-full tasting.
So I decided to try a third time. I added the rosemary water back to the canister, added the rest of my pack of rosemary (maybe 8 sprigs or so), charged it, swirled for a minute, then just let it sit for 5 minutes. It seems like it’d be hard to ‘break’ this, so why not hit it with a hammer, I figured. After 5 minutes, I discharged the canister, strained the result, and tasted.
This time I reckoned the result was as strong as the Alinea tea, but still not quite as full-tasting. It tasted very crisp and clean, like a japanese beer compared with a craft brew from the states. Just very straightforward, single-purpose.There wasn’t a ton of complexity. I asked Sarah to do a taste test for me, and she preferred the Alinea one, though affirmed that they both tasted good, strong, and very recognizably “rosemary-y”.
I think, however, that this method isn’t really superior because it was more expensive. It took much more rosemary, I had to do it in smaller batches, and it cost me 3 nitrous cartridges. Compare that to just boiling some water and pouring it over 2 sprigs. Even if I screwed it up and could have just done 1 infusion pass with 2 sprigs of rosemary for much longer, the only real savings was a time one. I think the method is much more useful with alcohol, which can’t be boiled; it’d be very effective for quickly infusing some vodka or bourbon or whatever, without losing any of the spirit itself.
I shot a video of all of this, narrating over it at the time. I was mumbling because Sarah was watching tv upstairs at the time, so the actual soundtrack was of me and Michael Scott talking simultaneously. So I decided to put some music over it. Except that YouTube mutes videos that use copyrighted music. So I downloaded the crappiest, cheesiest royalty-free music I could find, and will be using this music to score all future videos on this site as needed (the track featured in this video is called “Jazz Organ Breeze”. Excitingly, every track on this cd sounds like something from Flight of the Conchords). The last shot of the two liquids is me comparing the infusion (on the left) with the steeped Alinea tea (on the right). You can see a small color difference; the tea is browner, and the infusion is a little bubbly. I find the infusion prettier.