Alcohol and the Pressure Cooker

[percival]

I know that when cooking with alcohol, it takes quite awhile to actually burn off the alcohol content, even when boiling a stock/sauce at ~212 Fahrenheit, something along the lines of three hours to evaporate 90% of the alcohol.

My question is, how is the rate of evaporation affected by another 15 PSI, cooking at ~250 Fahrenheit within a pressure cooker? Only so much steam is released from the small rocker atop the pressure cooker, and though 250 degrees is well above what is required for alcohol to evaporate, the extra 15 PSI ups alcohols boiling point, just like water. Another concern is whether the alcohol would precipitate back into the pressure cooker as it cools, unless one rapidly releases the steam inside the cooker.

The purpose of this questioning is that I cook for my infant, and a little alcohol goes a long way here -- alcohol poisoning is a very serious issue, especially in smaller infants, as it's purely a weight issue. Now my kid eats everything -- duck feet, jelly fish, osso bucco -- but I'm concerned when I give him things like chicken teriyaki made with a mirin/sake reduction or a risotto made with white wine. If a pressure cooker can get the alcohol out relatively faster than normal boiling, great. If it actually evaporates less -- or none -- then that method's a no go, like sous vide.

Any ideas, folks?

And a bonus question for the scientifically inclined: how would I go about finding the actual alcohol content of say, a stew?

[lesliec]

Hi Percival.

I can't answer your specific questions, but have you tried burning the alcohol off? Even relatively low-alcohol liquids like wine flame happily once they come to the boil. Mind your fingers - I use a quick blast from my blowtorch to get the flames going, rather than faffing about with matches.

[percival]

Hi! I haven't tried igniting boiling wine by itself, but from what I've read, even igniting alcohol in a pan only burns off ~25% of the alcohol, before the proof drops too low for enough fumes to continue the burning. Of course, common sense says if you just keep the flame at it, eventually the alcohol will evaporate -- along with all the water and the wine flavor. I need a way to take out virtually all alcohol while still keeping the alcohol's flavors. Just doing some math, I figured that you really can't give a lethal amount of alcohol-stew to an infant -- they would have to consume far more liquid than their stomach could hold -- but they could still get very sick.

The simplest solution would be to skip using alcohol at all, but I'm trying to find a scientific solution, if one exists, that makes this possible. I don't have a chemistry background, so I don't know how to go about measuring the alcohol content, or else I'd have started experimenting already.

[Shalmanese]

Do you have any evidence that infants are especially sensitive to alcohol? True, they weigh less but they also eat less so they should consume about the same amount by bodyweight. The amount of alcohol left in typical food, after all the dilution from other ingredients tends to be less than 1%, not something that I would be especially worried about.

One effective way of reducing the alcohol content is to cook it longer with just the wine. For example, if the recipe says to add a cup of wine and simmer for 5 minutes before adding a cup of stock, instead add a cup of wine and simmer until it's been reduced by 3/4 and then add a cup & a half of stock. If you reduce by 3/4, then the alcohol must be reduced by at least 3/4 since it is preferentially boiled off.

[goldie]

What about making a wine reduction with some stock ahead of time and freezing it in ice cube trays? Then you could pop one or two in at the end of cooking for flavor, they would be nicely concentrated and not have much of an alcohol content. You would need to fiddle with it a bit, but I think it could work pretty well. My caveat would be to use homemade stock and dramatically reduce the salt so it doesn't screw up your seasonings while cooking.

Actually, if it works, the possibilities would be pretty good- you could do a big batch of veal stock (ideally) and have white wine, red wine, and port. You could do it in one day when you are stuck in the house and be good for at least a few weeks.

[Blether]

You could always give the child kid's food, rather than treating him as a

. Edited August 24, 2010 by Blether (log)

[budrichard]

The surface area for evaporation of a pressure cooker versus an uncovered pot/pan is quite smaller in a weighted cooker where the movement of the weight releases pressure as it controls the internal pressure in the cooker. I would expect that the evaporation of alcohol would be much less in the pressure cooker but how much less, I can't even begin to make an educated guess. Best would be to cook for a while with the cover off to evaporate as much alcohol as possible and then continue with pressure cooking.-Dick

[Tri2Cook]

I'm gonna go with Shalmanese and suggest maybe this is a case of making a mountain out of a mole hill. Cultures which use wine prominently in their cuisine have fed their foods to their children for a very long time without problems. Before Gerber and Similac, the kids fed from mom 'til they could handle what mom and dad ate. Then they ate what mom and dad were eating. Feeding a kid enough coq au vin for the residual alcohol to induce alcohol poisoning would be like trying to feed him/her enough lettuce to become obese.

That said, I also agree with Shalmanese' reduction suggestion. That's probably going to get you about as close to zero as you're going to get at home.

[percival]

Thanks for the feedback, folks. I think I will just have to reduce the alcohol on its own first prior to incorporating into stocks or deglazing.

Oh and as for feeding infants like little adults... anyone with a growing kid would know that they eat disproportionally far more than an adult. In my teens, I easily ate twice as much food as I do today, and I was much, much skinnier. My infant has consistently been in the 99th percentile for height and weight -- he's height-weight proportional for a kid easily a year/year and a half older than he currently is -- and can easily eat as much as an adult in one sitting, if I let him. Which I don't, cos I don't need a bowling ball child. If I wanted that, I'd treat him like a typical American kid and feed him deep fried chicken nuggets, soda, and Happy Meals.

[Blether]

Tou might also find some inspiration in the Substituting for alcohol in Cooking thread.

[percival]

Thanks for the link, Blether. Subs are a good idea. What's the ideal sub for cabernet sauvignon? For burgundy? Red wine vinegar adds far more acidity than normally found in red wine, which is less acidic than white wine.

Oh and just needed to point out one of your suggesions: raising your alcohol past ethanol's boiling point will in fact not boil off the ethanol, as alcohol -- wine, hard liquor -- is mostly water. And the two together boil off at different rates. Hence all this thread: if I could just selectively boil off the alcohol, I would.

[Blether]

Oh and just needed to point out one of your suggesions: raising your alcohol past ethanol's boiling point will in fact not boil off the ethanol, as alcohol -- wine, hard liquor -- is mostly water. And the two together boil off at different rates. Hence all this thread: if I could just selectively boil off the alcohol, I would.

Yes, I wrote that before I'd looked at the problem properly, which I did in relation to vinegar. It's more like the alcohol begins to come off at its boiling point, and continues to boil off until... the BP of water ? Something else ?

[budrichard]

When you reach the boiling point of a liquid its temperature will not increase. It takes heat energy to transfer from liquid to vapor during boiling and that need for energy keeps the temperature constant during boiling process.

For a mixture of two liquids such as alcohol and water, since the alcohol boiling point is lower than water, the alcohol begins to change state at a lower temperature keeping the bulk liquid at that temperature until the alcohol or most of it is gone. I'm not a distiller but that is why one can separate alcohol from mash(mostly water) in a distillery. I would think that for dilute solution of alcohol and water as in cooking, one could easily supply enough heat to cause the water to boil along with the alcohol and in the process convert both alcohol and water to vapor at the same time, thus getting rid of the alcohol faster.-Dick

[Syzygies]

To return to the original question, at ordinary atmospheric pressure alcohol boils off at about three times the rate of water. This rule of thumb always is stated with an asterisk, saying that the actual relationship is quite complicated.

At 250 F in a modern pressure cooker, is the ratio higher? Is this an effective technique for reducing alcohol? Put differently, is there any advantage to involving the pressure cooker?

This is a straight physics question to which I am wholly unequipped to guess the answer. At least I'm aware that I would be just guessing, and I'm not going to guess. Does anyone know?

(I found this old thread, researching how to use high alcohol beer as a liquid for making sourdough bread. In that application, alcohol can limit the growth of sourdough organisms, except those that feed on alcohol itself, changing the lactic acid / acetic acid balance of the result. But I am not interested in workarounds for my specific problem. I want to understand if there's a technique here. All of the proposed workarounds and commentary for the OP's question dodge answering the basic physics question he poses. My reason for needing the answer is entirely different, and a few years from now others will wonder this, with again entirely different motivations. So the physics question itself is worth answering, as stated.)

[Plantes Vertes]

Could you perhaps use alcohol-free wine? I've seen this in supermarkets. Otherwise cook the dish, remove the child's portion and then add the wine.

I also wonder whether unflavoured kombucha or rejuvelac might taste somewhat similar to alcoholic cooking ingredients. They're both fermented drinks so I suppose they contain trace alcohol, but not enough to intoxicate. I've never tried either of them so that's a long shot...

Edited April 1, 2013 by Plantes Vertes (log)

[sigma]

What is one to do?

[Plantes Vertes]

Or verjuice?

[Syzygies]

I reopened this thread to ask about the physics, because forum administrators don't like duplicate threads. Everyone is reading the original post and offering workarounds. My application is different. Please read the posting dates.

Does anyone know how using a pressure cooker changes the relative rates at which alcohol and water boil off?

[Plantes Vertes]

I reopened this thread to ask about the physics, because forum administrators don't like duplicate threads. Everyone is reading the original post and offering workarounds. My application is different. Please read the posting dates.

Does anyone know how using a pressure cooker changes the relative rates at which alcohol and water boil off?

Excuse me; I hadn't realised.

[FrogPrincesse]

I reopened this thread to ask about the physics, because forum administrators don't like duplicate threads. Everyone is reading the original post and offering workarounds. My application is different. Please read the posting dates.

Does anyone know how using a pressure cooker changes the relative rates at which alcohol and water boil off?

I would imagine that pressure would affect the ratio of alcohol in the vapor phase. See "Separation of azeotrope constituents" and "Pressure swing distillation" under this wikipedia article about azeotropes.

Edited April 2, 2013 by FrogPrincesse (log)

[Dexter]

I'm going to take a stab at this, but I'm sure there are others on the board that are better equipped to answer the question with proper authority and all. That being said:

A pressure cooker increases the temperature at which the food is being cooked by increasing the pressure experienced by the liquid (and food) within the vessel. As water hits its boiling point it converts to steam. That steam increases the pressure inside the vessel, making it "harder" for the remaining liquid to convert to steam. That means, it has to get a little hotter to do the same thing. What we are regulating in the pressure cooker is not the temperature (directly), but the pressure at which the food is cooking. This translates to higher temperatures, but it's really the pressure release point that is being manipulated directly.

Alcohol boils (azeotropic or pure, it really doesn't matter) at a lower point that pure water. But boiling as a physical process doesn't change. You are still going to increase the pressure within the vessel as you heat it. Because it boils at a lower temperature, it maximum pressure will be reached at a lower temperature than would be if you were using water. So, I would expect that alcohol in a pressure cooker would result in a lower cooking temperature.

Second point about pressure cooking - they aren't boiling off much water (or alcohol) at all, unless you are giving the vessel too much heat. You only really vent a considerable amount of vapor when you are above your pressure set point. Given this, if you could precisely measure the temperature at which you wanted the vessel to reach an stay, then you could theoretically boil off all the alcohol you wanted. However, this would require going above the pressure set point to release the valve - shaking weight, spring, or whatever. You'd also be releasing water vapor as part of the azeotropic complex.

Changing the rate at which the alcohol would boil off is rather more complex, and involves a lot of variables that I just don't have easy ways to account for quickly. My expectation is that the alcohol would come off somewhat more quickly at higher solution concentrations than it would at lower pressures, but that the practical differences would be negligible.

Edited April 2, 2013 by Dexter (log)