How do you rapidly cool pasteurized milk? Also, sous vide inquiry.
Would someone please help? We're pasteurizing raw milk using a sous vide method, suggested here at chowhound. We have the sous vide machine, a food sealing machine, plastic food bags, and a thermapen (for accurate temperature measurement), and now we need help in a couple of areas:
1: Can you do sous vide with milk if you're not vacuum-sealing the bag? Because it's liquid, I would imagine that vacuum-sealing would draw the milk out. Therefore, there will be air in the sealed plastic bag.
2. How do you rapidly cool the milk down after it's pasteurized? It will still be in the sealed plastic cooking bag.
Thank you very much.
1) not sure, doesn't it need to be completely submerged in the SV bath? And if you leave the container open and available to microorganisms, is the pasteurization going to be effective? You can vac-pack liquids, you just have to be careful (afaik).
2) ice bath
Sorry if this is a bit late. Here are a couple things.
1. You can, yes. If you don't have a chamber sealer (which handles liquids) you can find some ziplock bags that are made to handle sous vide so you can seal them with as little air as possible. I'm guessing you could also use a glass jar and make the liquid come up to/slightly over the liquid level in the jar as liquids transfer heat efficiently and all you want to do is get it to the proper temp and keep it there - plus for this type of thing it won't be sitting in the bath for a day or more (actually only around 90 minutes or so at the lowest temp range) so the slight amount of air should be fine. This page provides some useful guidelines: http://www.hi-tm.com/Documents/Chillf...
I'd note on that the temp you pasteurize at will also depend on what you want to acheive. To maintain the enzymes present in raw milk (at least mostly) then go lower for longer. If that isn't important to you then bringing the temp up to the higher level for shorter periods should work.
2. I agree with the ice bath for this. Once pasteurized you want it cooled down and put in the fridge quickly.