SubG posted:

Almost all the interesting things that happen in a piece of chicken happen between about 50 and about 60 C; it's where the fraction of soluble proteins starts to take a nosedive and the fraction of soluble collagen starts to rapidly rise. In a water bath this is going to be fairly homogeneous---the temperature in one part of a piece of meat will be pretty close to the temperature in other parts---while in conventional cooking you're going to see much more variability. This is important because meat's a pretty complex system, and when you give a temperature for the denaturing of a particular protein, this might be good for that protein in isolation, but the exact temperature an individual protein in a particular piece of meat will denature in actual practice will depend on a bunch of other factors, and so any number will be more of a probabilistic approximation than a scientific law or whatever.

My point here is that a surface temperature of 155 F/68 C (or whatever) might be something that a piece of chicken can hold up to via some methods (say deep frying) and you won't necessarily see all of the bad changes that negatively effect texture and mouthfeel, but in a puddle machine you're effectively moving the entire piece closer to the `brink' of that condition, so you might have problems at say 150 F/65 C.

I usually do poultry in the puddle machine at around 57 C/135 F to deal with this without having to dance around with having to do the whole hydrotherapy thing to cool the meat---I just rest it for a couple minutes between puddle machine and sear, which also gives it time to dry off a bit, which also helps with the sear. It's something you can play around with by feel---as long as you're holding for long enough (and the hold times around 57 C are around 45 minutes, so if you're doing a several hour cook this isn't an issue) there's no food safety issue, so you're just loving around looking for the texture and mouthfeel you like. Duck and turkey can handle being vizzled at lower temperatures without getting squoogy, but if I think the general belief in low temperature chicken having a hosed up texture is largely overstated. In any event, it's something that you can certainly just experiment with until you find what satisfies your personal preference.

...but has a specific heat of about half that of water (2.46 J/g °C versus 4.19). And the average household freezer is calibrated for about -18 C (0 F). So if the object you're trying to cool is at 60 C (140 F), then what you're interested in is the fact that a gram of pure ethanol at -18 C will eat about 192 J, while a gram of pure water at 0 C will eat about 251 J (to get either to 60 C).

You're much better off just putting a bunch of ice cubes in water and using that as a water bath if you want to cool something off quickly.