Sous vide without plastic bags
First of all, I agree with the others that there is no harm done by plastic bags for sous vide. I have read a statement by the manufacturer that brand name Ziploc bags don’t release anything below 76C. If you think how much a lawsuit could cost them if the information turned out to be wrong, I trust that they are telling the truth. For other brands, you may have to do some research about safe temperatures.
If you are still unconvinced, your choice of material is very limited. You say it must be airtight and waterproof; I’ll add that it must be pliable, so it can cover an irregular steak shape perfectly, without leaving air pockets, and it must somehow be able to create a seal. Also, it must not release any harmful chemicals by itself.
About the only thing that fulfills all criteria would be a wax with a high melting point, like carnauba wax. You could paint the steak with the melted wax, or, probably better, you could soak a piece of gauze in the melted wax and wrap the steak in it, pressing out any air bubbles. Then let it cool and set before cooking. The downside: not only is the food grade wax difficult to source for private people, it also can end up costing quite a bit.
Another option would be silicone, like the one used for baking pans. Unlike plastic, food grade silicone does not contain any chemicals which could leak the medical sector uses the same stuff for prostethics and implants; it is safe to have it inside your body, so it is definitely safe to cook your food mulberry outlet in it. The problem is that you’ll need a sealable bag made of silicone, and I don’t know if anybody manufactures such bags.
You might consider very tightly wrapping the meat in a caul (not necessarily an amniotic caul, a peritoneum should do nicely) and binding it, but I don’t know where you can get cauls. Maybe you can ask a butcher. Also, it probably won’t be mulberry outlet 100% watertight (but still enough to keep the tasty juices in the steak where they belong, instead of having them flow out into the water).
If you are willing to relax your rules a bit, you can solve the problem much easier. I think you will agree that whatever hypothetical substance might leak from a plastic bag, it cannot travel far through a solid medium. So a steak wrapped in something protective and then sealed in a plastic bag should be safe you just discard both the plastic bag and the presumably contaminated protective substance. Yes, it is possible that meat juices that have come in contact with the plastic bag end up on the steak, but the possible contamination should be hundreds of times less than if direct contact is allowed between the plastic and the meat.
If you can live with this option, the usual insulators used in the kitchen should do. They are plant leaves I’d use grape leaves, but you can use practically anything that is big enough and batters, like tempura batter (breading leaves an irregularly shaped surface, so I won’t consider it here, you’ll end up with lots of miniature air pockets). If using a batter, you will want to first set it in a pan with very hot oil, just hold it there long enough to set the batter, but not enough to warm the meat on the inside above the sous vide temperature. Both of these options wont’t function mulberry outlet on their own, as they won’t create a sealed waterproof barrier. But combined with a plastic bag and later discarded, they should be a good solution. The leaves will also add a nice taste of their own. Still, it shouldn get actually liquid, so there shouldn be any currents inside mulberry outlet the batter to bring contaminant molecules from the outer side to the inner side. We are speaking diffusion of big molecules (Bisphenol A is C15H16O2) through a solid, which is extremely slow, and happens with only a miniscule fraction of the molecules present on the batter, and the plastic batter and batter meat interfaces also don let through much molecules. It not perfect, but should work.
You could also consider a combi oven or water vapor oven. They’re sometimes called “sous vide without bags”. The very moist air is a great heat conductor and foods come out just beautifully. But the ovens are not cheap.
Keep in mind that not all plastic is created equal, and while not all of it is heat stable at the temperatures we’re discussing some of it is very, very stable.
Polyethylene (NOT polypropylene!) is a great sous vide and freezer storage plastic. It’s also used in cryovac, which means that your meat was likely stored and wet aged in it prior to final butchering at point of sale. It’s the plastic found in Rival Seal a Meal, FoodSaver and Ziploc. Also no PVC or phthalates. I’ve been told some off brands use different plastics (NOT verified!), and that’s one reason why I don’t use other brands. Let it float on top of the bath.
It will only work if your sous vide cooker has a lid. If you don’t have a lid over the bath, the bowl will not heat through. I tried without cooker lid and failed.
It also takes way more room in the cooker than bags do. Only useful if you heat just one portion.
For vegetables at 90C it worked perfectly.
For meat at 54C it worked very much slower than a bag. Still, if you can leave it in long enough, it will work.
I found it unsuitable for steak and fish, because of the increased cooking time and uneven heating, even with turning the goods. But I will always use it for hot stuff like veggies.
I’ve been thinking of cooking fish and beef fillets using Pyrex dishes filled with vegetable oil as a good conductor of heat around the food. Chefs have been oil poaching fish for ages. Air is not such a good heat conductor, thus air is removed out of the foodsaver bags. Sure, some of the juices of the fish or beef will end up in the oil bath, but I’m willing to sacrifice a little of that for my health. Plastics leach many chemicals with and without heat (we never heat IV bags and tubes, yet it’s proven they leach harmful chemicals) so just knowing BPA is taken out (only after the consumer outrage) doesn’t make me feel any better.