We’re all familiar with the ubiquitous single use bag that can be found in any grocery store or big box retailer these days—the one where you get your groceries home and then throw it away.
It seems like a no brainer to me to make our lives easier by using this type of packaging for everything from food to garbage.
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what about when we need to vacuum seal something? Can those bags touch sous vide water bath temperatures?
Let me start off by saying I don’t have an answer for you. I know very little about vacuum sealing other than what my mother taught me over thirty years ago.
She told me that if you put meat in a bag and zipped up the top, it would keep its shape better because there was less air circulation inside.
This has been true ever since I learned how to zip tie as a kid. So I tried it out on some chicken breasts.
I used a standard size Ziploc brand freezer bag and cut four small holes at the bottom corner to help ventilate the bag during cooking.
Then I seared both sides to about 135 degrees Fahrenheit (57 degrees Celsius) and cooked them for 20 minutes each side. After they were done, I took them out of their bags and let them cool for a few minutes before slicing into them.
They looked great! No visible signs of shrinkage or discoloration. In fact, they were so good looking that I almost wanted to serve them to someone else. Almost.
If you want to vacuum seal something, go right ahead. You could even do it while the item is still hot. Just remember to take care not to puncture the bag. If you plan to cook with the bag intact, though, make sure you leave enough room for the steam to escape through the holes you made.
Now that I think about it more, I realize that many vacuum sealed foods look perfectly normal after being cooked. For example, most people wouldn’t guess that steak tartar sauce was actually vacuum packed until it’s sliced open.
So there’s really nothing wrong with vacuuming things up. As long as you can smell the product coming out of the bag rather than getting sucked in, I see absolutely zero reason why your bag shouldn’t work for sous vide cooking.
That brings us back around to the original question: Why bother with vacuum sealing anything? There are plenty of reasons to vacuum seal stuff, but I’ve never had much luck finding examples of when it’s useful for sous vide.
My best bet is to find recipes that call for vacuum packing instead of wrapping things tightly in foil or wax paper, which doesn’t always result in the same level of protection against moisture loss as a vacuum pack.
The main advantage of a vacuum pack is that it prevents water from soaking into the material surrounding the food, such as aluminum foil, which can cause metal parts to rust.
Vacuum packs also reduce condensation between the air and the surface of the food, which leads to frosty crusts.
Lastly, the lack of air circulation helps prevent oxidation, which can lead to browning. None of these factors are particularly relevant for sous vide.
There is one exception, however. When using sous vide to preserve fresh herbs, you should definitely vacuum pack them.
Heat destroys enzymes, which are needed to slow down the process of oxidization. Herbs that have been stored under refrigeration will lose their vibrant color within a couple of weeks without proper storage.
However, herbs exposed to oxygen quickly turn black and stay that way. Vacuum sealing keeps oxygen from reaching the herb and preserves its bright green color indefinitely.
So now you know all about vacuum sealing, you might be wondering whether plastic bags can withstand sous vide temperature. Fortunately, they can.
Plastic bags have a thick layer of polyethylene resin on the outside, which makes them impervious to liquid penetration. The inner layers are composed of multiple types of plastics, including nylon 6 and nylon 11. These materials allow the bags to retain heat well enough to keep liquids contained.
As far as I know, there aren’t too many situations where plastic bags are superior to regular ones. A thin layer of oil coating the exterior of a bag makes it slightly slippery, which means it can slide around when you’re trying to pull it across a table or hold it upright.
Also, because the bag isn’t completely sealed, it allows some of the vapors produced by the food to escape. Both problems can be avoided by making sure that the edges of the bag are taped properly.
Finally, if you notice bubbles forming in your bag, stop immediately and try another method. Bubbles indicate moisture trapped inside, which means the bag has already started breaking down.
In short, vacuum sealers aren’t strictly required for sous vide cooking; I’m simply pointing out that unless you’re preserving herbs, they’re probably not worth buying.
One last note about vacuum sealing: Even if you’re careful not to damage the bag, you may end up with a hole somewhere along the edge. That’s okay; you can patch the hole later with tape.
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