One of the more common questions I am asked is "What is the best way to seal your food for sous vide cooking?". There are so many options for sealing your food that it can get confusing figuring out exactly what you need. There are several ways of doing it, ranging from large chambered vacuum sealers costing over a thousand dollars all the way down to Ziploc bags from the grocery store. Here's the low down on what you'll need to master the art of sealing your sous vide food.
Since sous vide means "under vacuum" people understandably believe the vacuum sealing process is critical to sous vide. However, this actually isn't the case at all. With a few minor exceptions, getting an actual vacuum seal isn't nearly as important to the sous vide process as removing most of the air is. There are a few things accomplished by sealing the food as well as by removing the air.
You don't want the food directly in the water or the water leaking into the sous vide pouches. Sealing the food traps all the juices and flavor in the bags instead of losing it to the water bath.
Bags with air in them float, leaving parts of the food out of the water and potentially at dangerous temperatures. The more air you pull out, the less chance of floating you will have.
Air is a really poor transmitter of heat compared to water (you can stick your hand in a 400°F (200°C) oven for a few seconds but sticking it in much cooler boiling water will scald you almost instantly). So removing all the air from the sous vide pouch will result in a faster and more evenly cooked food.
The biggest advantage vacuum sealing has over other types of sealing is that you can store the food for a longer time before and after cooking it. This is especially helpful in restaurants but usually doesn't come into play for most home kitchens.
Here are the most popular methods of sealing food for sous vide cooking.
The best, but most expensive method, of sealing food for sous vide cooking. Chambered vacuum sealers are large devices that can suck the air out even if there are liquids in the bag. They usually have a variable vacuum strength you can set which is great for other modernist techniques like compression and infusing. The cost of bags is also pretty small for chambered sealers, running about $0.14 per bag.
However, chambered vacuum sealers do come with downsides. They tend to run at least $500 and up to more than $1000. They are also big and heavy, most weigh between 50 and 85 pounds (22 to 39 kilograms) which makes then hard to move from the counter top.
The most consistently highly rated chambered vacuum sealers are the VacMaster brand sealers. The two most common models are the VacMaster VP210 and the less powerful VacMaster VP112. Most of their models are highly regarded.
Edge sealers are a good intermediate step if you want the power of a vacuum seal but don't want the bulk or expense of a chambered vacuum sealer. They are much less expensive, usually around $100 to $200 and are small and portable. They are also great if you pre-package a lot of food at home since they help food last a lot longer in the freezer without getting freezer burn.
The largest downside to edge sealers is that they can't effectively seal bags with liquids in them. The pump will pull the liquids out with the air, preventing the bag from sealing well. Edge sealers also can't pull too much of a vacuum compared to chambered sealers and are usually not adjustable.
The bags themselves are also very expensive, usually about $0.75 per bag, or 5 times what a chambered sealer or Ziploc bag costs. I know several people who prefer Ziploc bags and set aside the $0.50 difference every time towards saving up for a chambered vacuum sealer.
Many people are surprised when I tell them that the type of sous vide pouch I use most often is standard Ziploc Freezer Bags, usually in the gallon size. They are inexpensive, easy to find, and very easy to use. They get almost as good of a seal as the edge sealers if you use the Water Displacement Method. They also handle liquids better than edge sealers so you can use sauces and marinades in your sous viding. And of course, the upfront cost of $5 is hard to beat!
Another thing I really like about using Ziploc bags is that they are easy to open and re-seal. Many foods like sirloin, brisket, and pork shoulder have a lot of variety in the toughness of the meat and need different lengths of cooking time, which can be hard to determine before actually cooking them.
With Ziplocs I can open the pouch after the minimum amount of cooking time has passed and check the tenderness. If it needs more tenderizing I just re-seal the bag and put it back in the sous vide machine for a few more hours. When it's tender enough, I'll pull it out and it's ready to serve whenever I want. It really helps prevent under- and over-cooking foods.
Opening and re-sealing the bags is also helpful if the food has given off some gas and is starting to float. This often happens during longer cooks and it can be a pain to try and weigh down the bags. With Ziplocs, you can release the gas, re-seal the bag, and the food will easily stay below the water again.
The downside to Ziploc bags is the occasional leakage of water, especially for longer cooks at higher temperatures. If I'm cooking for longer than a day I'll often use my FoodSaver or at least double bag the food.
Depending on the type of food you are cooking you can also use high-quality saran wrap, mason jars, oven bags, and ceramic ramekins. There are also hand pump bags, sous vide-specific "zip-top" bags, and other miscellaneous sealers but I've found that unless you're doing something specific (ramekins work great for custards, saran wrap is wonderful for roulades, etc) either a chambered sealer, edge sealer, or Ziploc bag works best.