Quick Infusions by N20 Cavitation

[slkinsey]

Aren't we talking about N₂O, not nitrogen? I would guess it's ability to enhance extraction of flavour compounds has more to do with the pressure allowing diffusion in and out of the material and its resonance structure giving favourable polar/non-polar attributes to transfer the compounds to the alcohol/water phase.

Yes, we're talking about N2O and not N2. But this is just because it's not practical to use N2 at home or in a bar or kitchen. It takes much more pressure to get N2 to dissolve into liquid than it takes for N2O. It's a lot easier to get ahold of N2O. And you can use a cream whipper. The reason we want to use a gas with poor solubility into liquid at atmospheric pressure is because the technique works due to the rapid formation of bubbles (this is why we use N2O and not CO2 -- because N2O comes out of solution effectively immediately once the pressure is released and CO2 doesn't).

Let's say you want to make a basil infusion into tequila. You put some basil leaves and tequila into your cream whipper. You charge the whipper with N2O. This does two things: it dissolves N2O into the tequila and it also forces the tequila into the basil. Then you rapidly release the pressure and the N2O rapidly comes out of solution. Inside the basil leaves, the rapid formation of N2O bubbles tears apart cell membranes, etc. And this liberation of cell contents causes accelerated infusion of the basil into the tequila.

The mechanism (rapid formation of bubbles upon release of pressure) using N2O is the same as it is using N2. I'm sure that N2 would be even more effective, but it's just not practical to use in a home, restaurant or bar.

[jrshaul]

I'm not entirely so sure of that. The homebrewing community has started picking up on "nitro", and some canned beer is actually nitrogen-carbonated as well. The pressures required are much lower, of course, but high-pressure vessels aren't that expensive.

Nitrogen can, however, impart a flavor to the liquid, much as CO2 can leave behind a "flat soda taste." I'm not sure if it's the cause, but I do know that bubbling nitrogen through water produces nitric acid (slowly!)

[haresfur]

The reason we want to use a gas with poor solubility into liquid at atmospheric pressure is because the technique works due to the rapid formation of bubbles (this is why we use N2O and not CO2 -- because N2O comes out of solution effectively immediately once the pressure is released and CO2 doesn't).

I'd like to see the evidence that this is what's really happening and is the major effect, rather than a dual solvent extraction. Especially since the above article shows a difference with different infusion time but no difference with slow vs fast relief of pressure.

What's the solubility of CO2 in alcohol?

[slkinsey]

The reason we want to use a gas with poor solubility into liquid at atmospheric pressure is because the technique works due to the rapid formation of bubbles (this is why we use N2O and not CO2 -- because N2O comes out of solution effectively immediately once the pressure is released and CO2 doesn't).

I'd like to see the evidence that this is what's really happening and is the major effect, rather than a dual solvent extraction.

The "evidence" is that it's believed to work by the same action as very-closely-related nitrogen cavitation. Absent someone willing to run extremely expensive tests on extremely expensive scientific equipment to verify exactly what happens, the most plausible explanation is that it work similarly to N2 cavitation. Certainly we should expect similar things to be happening (i.e., disruption of cell membranes, etc.). We know this is a root cause of decompression sickness, for example.

Especially since the above article shows a difference with different infusion time but no difference with slow vs fast relief of pressure.

Modernist Cuisine has a short section on pressure marination (3-207). They explained that in their tests meat gained 2% of its weight in marinade after 1 minute, 4% after 3 minutes, 5.3% after 5 minutes and 6.3% after 20 minutes under pressure. This explains why there is a difference with infusion time: because the alcohol/water (and dissolved N2O) penetrates more thoroughly into the flavorful substance as time increases.

The reason there is no pronounced difference between slow versus fast relief of pressure (whether there might be a measurable difference is another question, and one to which we don't have an answer) is that there isn't all that much difference in this technique. More accurate might be to describe it as "fast versus very fast" relief of pressure. It's hardly the case that "slow release" is following an 18 hour decompression schedule, like a diver ascending form depth, so that no bubbles are formed. Rather, what we're talking about here is blowing all the pressure out with one big blast of the trigger ("fast") versus letting the pressure out slightly more gently over the space of a minute or so ("slow"). In the slow method, there is still plenty of bubbling.

The best guess, then, is that the effect is accomplished by some combination of (a) increased penetration of the solvent into the flavorful material (as per the Modernist Cuisine example); and (b) disruption of cell membranes, etc. by cavitation (as comparable to N2 cavitation in laboratory cell work). A similar effect of rapid infusion can be observed using CO2 instead of N2O. This is not preferred because some of the CO2 stays in solution, resulting in a carbonated liquid with added H2CO3. So there's nothing special about N2O except that it has poor solubility in water and ethanol at atmospheric pressure.

I suppose if you wanted to do an experiment to show with certainty whether cavitation was responsible for a large portion of the effect, you'd have to figure out a way to compare a rapidly-released infusion versus one which was released slowly enough to outgas the N2O with no bubbling (normalizing for contact time between the solvents and the substance).

Edited January 16, 2012 by slkinsey (log)

[jrshaul]

I tried a cocoa infusion using the method on the Cooking Issues blog. The end result had a very faint cocoa flavor - next time, I'll try grinding it in the food processor to increase surface area. Definitely did something, though.

http://www.cookingissues.com/2010/09/29/star-chiefs-%E2%80%93the-cocktail-demo-with-recipes/

[e_monster]

I tried a cocoa infusion using the method on the Cooking Issues blog. The end result had a very faint cocoa flavor - next time, I'll try grinding it in the food processor to increase surface area. Definitely did something, though.

http://www.cookingissues.com/2010/09/29/star-chiefs-%E2%80%93the-cocktail-demo-with-recipes/

Did you use the kind of cacao nibs he mentions? Everyone that has posted about the cacao infusion has mentioned that the results are highly dependent on the quality of the nibs.

[cschweda]

Did you use the kind of cacao nibs he mentions? Everyone that has posted about the cacao infusion has mentioned that the results are highly dependent on the quality of the nibs.

I used these nibs:

http://www.amazon.com/Navitas-Naturals-Cacao-Nibs-8-Ounce/dp/B000OQ4A3S/ref=sr_1_2?ie=UTF8&qid=1328029734&sr=8-2

Infused for 3 minutes in relatively inexpensive Vodka (i.e., not premium).

The chocolate flavor was great -- and grew even better after 24 hours. I did nothing to the nibs -- just dumped about 50g in with some vodka (not exact measurement). Used the iSi Gourmet Whip, one N20 cartridge, infused, shook for 30 seconds, let sit for 3 mins, vented quickly. Great cocoa taste -- no bitterness. It's interesting because while the cocoa was pronounced -- very pronounced -- it wasn't at all cloying or heavy. Very nice!

Edited January 31, 2012 by cschweda (log)

[jrshaul]

My nibs came from Whole Foods, and are not so good. I'll try the brand you recommend.

What temperature was the vodka during infusion?

[e_monster]

My nibs came from Whole Foods, and are not so good. I'll try the brand you recommend.

What temperature was the vodka during infusion?

By the way, I recommend using decent vodka. I made a few infusions with cheap vodka and the results were definitely sub-par. Stoli seems to work pretty well and is not terribly expensive. If there are cheaper brands that are smooth, I'd love to know.

[thirtyoneknots]

My nibs came from Whole Foods, and are not so good. I'll try the brand you recommend.

What temperature was the vodka during infusion?

By the way, I recommend using decent vodka. I made a few infusions with cheap vodka and the results were definitely sub-par. Stoli seems to work pretty well and is not terribly expensive. If there are cheaper brands that are smooth, I'd love to know.

Monopolowa and Luksusowa are both very good, run about $11/750ml.

[cschweda]

Agreed about the quality of vodka. When I make this again (yhis weekend), I'll buy something a bit better than the no-name six-dollar bottle.

BTW -- everything was at room temperature.

[e_monster]

Agreed about the quality of vodka. When I make this again (yhis weekend), I'll buy something a bit better than the no-name six-dollar bottle.

BTW -- everything was at room temperature.

All my infusions were done at room temperature as that was what Dave recommends in the article. My harsh infusions were done with Smirnoff and Burnett's. Both were very harsh and put the lie to my belief that cheap vodka wouldn't be that much different from a half-decent vodka.

[cschweda]

All my infusions were done at room temperature as that was what Dave recommends in the article. My harsh infusions were done with Smirnoff and Burnett's. Both were very harsh and put the lie to my belief that cheap vodka wouldn't be that much different from a half-decent vodka.

Yep -- I found the same thing. Cheap vodka is insanely harsh. I tried an infusion earlier this evening with Absolut. Fantastic. Not harsh at all but with all of the cocoa flavor. Used 50g of nibs again. Turned a dark brown, but I notice (after a couple hours now) it's not quite as dark.

[evo-lution]

My nibs came from Whole Foods, and are not so good. I'll try the brand you recommend.

Chiming in a little late here but if you can get your hands on them I recommend Valrhona Grue De Cacao (cocoa nibs). Possibly a little pricier but worth parting with the extra coin if that's the case.

[bhsimon]

By the way, I recommend using decent vodka. I made a few infusions with cheap vodka and the results were definitely sub-par. Stoli seems to work pretty well and is not terribly expensive. If there are cheaper brands that are smooth, I'd love to know.

 

Slightly sideline to this topic, but potentially very useful. I've done a few tests filtering low-quality vodka with impressive results. Using an expired Brita water filter, we pass inexpensive vodka through the filter 3 times. Good results can also be achieve after 2 passes. There is little gain with 4 passes.

 

This process markedly improves the perceived quality of the vodka, and as been preferred by all of the 10+ participants in my triangle discrimination tests.

 

This might be useful for those wanting to experiment with the rapid infusion process without going through their expensive vodka. Once a preferred formula and method has been derived, it could be applied to the top-shelf vodka.

[Hassouni]

Morgenthaler has an iSi video where he "barrel ages" a negroni in his iSi with oak chips. However, he lets it rest overnight before venting the gas out.

 

I was wondering what the purpose of that is - and does letting it rest longer infuse more flavor in?

 

For example, in one of Dave Arnold's videos, he infuse mint into water and charges it with CO2 to create mint soda water. However, he doesn't really let it rest, and the water barely turns green.  When I've infused mint into Everclear, the booze turns bright green within a couple hours or so. 

 

So here's what I don't get. 1) The instant infusion thing is the equivalent of a couple weeks traditional infusion. So how come the mint in Dave Arnold's video didn't turn the water bright green? Does water not extract the color as much? 2) What is an overnight rest + nitrogen cavitation the equivalent to in terms of traditional infusion/aging?

[FrogPrincesse]

1) Exactly. Chlorophyll is very soluble in alcohol, but insoluble in water.

[Hassouni]

Well, that solves that. Merci!

 

How about No. 2?

[FrogPrincesse]

Well, that solves that. Merci!

 

How about No. 2?

 It's going to be dependent on pressure & temperature in your iSi.

[Hassouni]

Well assume 750ml of booze, a 1L iSi, and 2 nitrous charges

[FrogPrincesse]

Just send me a couple of iSis (and the booze), and I will do the research for you.

[Hassouni]

I might. I got a pretty good condition used 1 L Gourmet Whip on eBay the other day and today I discovered it doesn't include the fucking charger holder, rendering the entire device useless!

[JoNorvelleWalker]

Creamright sells spare parts but you might as well have purchased from them in the first place.

 

Edit:  the charger holder is $12.00.

Edited September 27, 2014 by JoNorvelleWalker (log)

[Hassouni]

Yeah, just found that. I think I have to resort to that.