How To Remove Air From A Freezer Bag

There are 2 ‘musts’  for successful sous vide cooking:

  1. You must put your food in a plastic bag (unless it’s an egg with a shell).
  1. You must remove as much air from the bag as possible.

Let’s take a look at these in turn.

Put the Food in a Plastic Bag

This is easy. Take the item that you want to sous vide and put it in a plastic bag. Done.

Having said that, you should use bags made of food grade plastic as you don’t want any nasty chemicals leaching into your meal. 

Also, it pays to buy good quality, specially designed bags, rather than popping your steak into a random ziplock sandwich bag and dumping it in a water bath. There is nothing worse than leaving a lovingly prepared chicken breast swimming around in its bath for 2 hours, only to come back and find that the bag has split and your chook is waterlogged.

Steak in a vacuum sealer bag, ready for the sous vide method of cooking with rosemary to the left and potatoes and garlic to the right.

Remove as Much Air from the Bag as Possible

This can be a bit more challenging.

If you have a vacuum sealer, popping the food in a plastic bag and expelling the air from it is fairly straightforward. Yes, in a perfect world you’d use vacuum sealer bags made to get the best results from your particular machine. However, you can still get a great seal on with a vacuum sealer and a strong freezer bag.

If you’d like to know all about the wonders of vacuum sealing food and why a vacuum sealer is a great accompaniment to a sous vide machine, you can read more here.

Now if you don’t have a vacuum sealer, you have 3 options:

  1. Squeezing the air out – Put your steak in a regular freezer bag and use your hands to squeeze as much air out of it as you can before you zip it closed. It doesn’t give 100% perfect results, but it will do at a pinch.
  1. Using water displacement – Put your steak in a regular freezer bag and then lower the bag into a pot of water, keeping the open end above the surface of the water. As you lower the opened bag, the water outside it will force the air out of the bag. When the opening of bag is almost submerged, seal it closed. This can be a quite fiddly and actually really annoying if you submerge your bag of food just a fraction too much and end up with water flooding into it. However, a bit of patient and practice certainly helps.
  1. Sucking with a straw – Put your steak in a regular freezer bag and pop a straw into one end of the opening. Zip the bag closed up to the straw. Suck the air out of the bag using the straw, then remove it and seal the bag. Whilst it works, we don’t recommend this method as it’s not the most hygienic way to create a vacuum in a plastic bag, plus the taste of raw steak isn’t all that pleasant!

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