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Both Costco and my butcher regularly sell meat that is prepackaged in cryovac packages, is it safe to sous vide these store bought packages? Or do I need to repackaged them before cooking? It seems like it would work fine but I wasn't sure. - Jonathan
Out of all of the questions I'm asked, this is probably the most common one! It makes sense because the allure of buying some pre-sealed meat, placing it directly in the sous vide machine, and having a great meal is so enticing. Unfortunately, as with most common questions, the answer really is "It Depends".
Note: If you prefer, you can jump right to the Lesson Recap.
This is mainly because when we talk about prepackaged foods there is a really wide range of types of meat and types of packaging used. These can range from high quality beef your local butcher vacuum seals for you, to cheap flimsily-wrapped chicken bought in bulk, or even marinated and seasoned meats. Depending on what type of packaging and meats you are using there's a wide range of safety and flavor information.
There are three main questions we will look at: 1) Will the store-sealed bags stay sealed, 2) is it safe to sous vide in store packaged bags, and 3) will there be flavor loss from store bought cryobags.
Note: I'll discuss all three questions and show that there are often many times you can cook directly in that packaging. However, I almost always repackaged my meat before cooking it unless I fully trust the packaging it came in. I tend to err on the side of safety, especially since it's often only a minor gain in convenience.
This is perhaps the easiest question to answer.
The two general types of packaging used by stores are heat-sealed and glued. Heat sealed packaging will not leak unless there is a hole in the bag or it has a bad seal. Glued packaging will almost always leak or even come fully apart.
There are a few ways to tell if prepackaged meat is heat-sealed or glued.
Many packages are designed so you can peel off the packaging and easily remove the meat from inside. These are almost always glued.
Most heat-sealed packages will have a rough pattern where the seal is, often a zigzag or crosshatch pattern where the two sides were melted together.
If you are unsure of the type of bag, it's usually best to stay on the safe side and rebag it.
This is a much more difficult question to answer than whether or not the bags will leak. The biggest issue in sous vide safety when using prepacked bags is determining what type of plastic is being used.
There are various kinds of plastic bags, some are not food safe at all, some are food safe only at low temperatures, and some are food safe even at or above boiling. Sous vide should always be done in bags that are food safe up through boiling (or at least the temperature you plan on cooking your food at).
The concern with non-food-safe bags is the leaching of chemicals into your food. Not only is this unsafe, potentially leading to cancers and other issues, but it is also invisible. This means that you will not see any immediate issues when cooking with unsafe bags.
ChefSteps had a nice writeup about this subject:
According to the latest research that we're aware of, the safest plastics are food-grade high-density polyethylene, low-density polyethylene, and polypropylene. Virtually all sous vide bags are made from these plastics...
...other plastics that may be in your kitchen, such as inexpensive, bulk plastic wraps (still commonly made from polyvinyl chloride or polyvinylidene chloride), can contain harmful plasticizers that have been shown to leach into fatty foods such as cheese and meat. We do not recommend using these, ever.
- ChefSteps, Is Sous Vide Plastic Safe?
If you are sure the store is using high-quality, food-grade plastic rated for high heat, then they should be just fine. Otherwise it's normally best to re-bag the food yourself.
It is often hard to tell what type of plastic food is packaged in but there are a few things you can check to try and get an idea.
The easiest way is to contact the store you bought it from, or the company that produces it. Just send them an email, or call them, and ask what type of plastic they use in their packaging. You can also ask if it is rated for low-temperature cooking temperatures.
Asking about the type of plastic is obviously easier if you are dealing with a local butcher or small store you frequent often but sometimes large companies will still get back to you. For instance, someone wrote into Foster Farms Chicken to ask if they could cook in their bags and got this in response:
Getting the information directly from the company is often your best bet.
If packaging is labeled as "microwave-safe" or "boil-safe" it is usually fine to use with sous vide.
Many plastic containers have codes on the bottom indicating what type of plastic they are made from. Recycling New Jersey explains how to find them and what they mean, as does io9. For those in the UK, here is a list from CS Recycling, though I believe they are international symbols and should be the same.
My general rule of thumb is to assume the store used the cheapest packaging they could get away with. If I don't know what type of plastic it is I always just take the 5 minutes and repackage the food in my own sous vide bag to be safe.
There are a few other minor safety issues to be aware of.
Another safety issue with sous viding directly in store packaging is missing other things that are in the package. Some packages of meat contain absorbent pads on the bottom. These pads are often obscured by the meat and packaging, and they are almost never rated for cooking temperatures.
Some packages also contain small pouches of spices or preservatives, wax paper, or other inserts, all of which are rarely safe at cooking temperatures.
While not a safety issue, be aware that placing packaging in your sous vide water bath will usually strip off all labels affixed to it. These labels can get caught up in your sous vide machine and should be removed before cooking.
Some prepackaged meats come stacked on top of each other in the container, multiple racks of ribs are a very common example of this. If you leave them stacked, you need to be sure you extend the cook time long enough to penetrate the additional thickness of all the layers.
There are a few variables to consider when thinking about how flavor will be affected by cooking directly in the store packages.
Many prepackaged foods are simply raw, unseasoned meat. When you are sous viding these in the bag they came in from the store there will definitely be some flavor loss. Or more precisely, there is no way to add additional flavor to them.
This is because usually you would want to season your meat before cooking it. This can mean spice rubs, herbs in the sous vide bag, or simply salt and pepper. If you never open the pouch, you can't add those flavors to it.
While it does result in slightly less flavorful food, I know many people have found that the tradeoff is acceptable for the ability to add the package directly to the water bath.
Many prepackaged meats come in marinated or pre-seasoned packages. These will have no flavor loss if they are cooked directly. Most of the time these types of meats are packaged so you just cook them directly anyway.
Just make sure that the standard directions don't instruct you to wash off the marinade before cooking. This is usually true for very salty marinades and brines, such as those used with corned beef.
Some meats that are meant to be normally braised will also be overly salty to compensate for being cooked in water and might not turn out well through sous vide.
If cheap, unsafe plastic is used then there can also be leaching of flavor and aroma into the food...definitely not something you want!
Similar to not being able to season prepackaged foods, you also can't trim and clean the food. Many cuts of meat do best with some prep work before you cook them, such as removing the membrane from ribs or the silver skin from pork tenderloin.
If you don't open the package you can't really trim and clean the meat until after it has been cooked. For most cuts this isn't a big deal, but it's something to keep in mind if you are working with food that traditionally needs some trimming before you cook it.
Hopefully now you can make the decision about whether or not to sous vide directly in the packaging from the store.
In this lesson we discussed whether or not it is ok to sous vide food in the store packing it comes in. We looked at:
I also linked up some more relevant information including:
Have questions or comments of your own about this?
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Thanks again and happy cooking!
Jason Logsdon, Amazing Food Made Easy