Precautions and Contraindications with vacuum packaging and sous vide cooking

Vacuum packaging of food is not very well known by the general population and sous vide cooking, even less so.

This is why we want to make sure you have access to all the information you need in order to have the best experience possible with these techniques.

Under vacuum means we have removed all ambient air while packing the food.

This helps a lot but on its own, it’s not enough to make sure your food stays fresh. In certain cases it could even cause problems. You can access general conservation guidelines table for food products here

As previously mentioned in our article on vacuum packaging, air is the enemy of food with regards to colour, humidity level, molds and other microorganisms that may be present in the food.

There are exceptions such as fish, seafood, certain fruits and vegetables as well as certain types of cheese.

Fish and seafood precautions

Raw fish and seafood need special attention when it comes to vacuum packaging.

Raw vacuum-packed fish CANNOT BE stored in the fridge
Before you pack your fish under vacuum, be attentive to potential conservation issues.
Packing fish under vacuum and leaving it in the fridge is a very dangerous HEALTH HAZARD.
Fish and seafood under vacuum MUST be kept in the freezer.

As soon as you take it out of the freezer, you must pierce the vacuum packaging to allow it to come in contact with oxygen.

Fish and seafood are naturally contaminated with bacteria called clostridium botulinium which is responsible for botulism.

This bacteria dies during cooking and cannot develop when fish is in contact with air (oxygen). However, a refrigerated vacuum package makes its development easier.

Fish and seafood under vacuum should be kept in the freezer.

We recommend that you vacuum package only the fish that you will either freeze immediately or that you know for sure you will eat cooked. When thawing your fish, make sure you open the bag if you want to eat it raw (smoked salmon for example).

General contraindications for vacuum packaging

Vacuum packaging is not a one size fits all. Some food needs to breathe, release gases, are too mushy or simply should not be kept under vacuum.

Some foods you should not put under vacuum:
  • Soft cheeses such as brie or camembert
  • Mushrooms
  • Cruciferous vegetables such as cabbage, cauliflower, broccoli etc
  • Onions
  • Garlic
  • Fresh bread (the vacuum will crush it when taking all the air away)
  • Any soft, mushy or delicate food that the vacuum process might crush.

In some cases, we can work around the problem by blanching the vegetables or pre-freezing soft food before you put them under vacuum.

Further reading about vacuum packaging:

Food safety in sous vide cooking*
*Extract from the following cook book: Sous vide simple - 4 simple steps to delicious meals; Edited by Mary Dan Eades; Paradox press
As with all cooking methods, it is important to use clean, fresh ingredients and to work with clean hands and tools on clean surfaces. 

When cooking food sous vide for immediate consumption&mdashwhat is termed Cook-Serve&mdashthe basic rules of food handling will suffice, because the food will remain hot in the machine until serving and may even get a final high-temperature sear.

Sometimes, especially when entertaining, it is helpful to employ a technique, used widely by restaurant chefs, called Cook-Chill-Hold. In this method, food is vacuum sealed and cooked to completion in the water oven in advance, and then quick chilled in an ice water bath for long enough to return it to refrigerator temperature, and out of the so-called “danger zone.” The danger zone is the temperature range between 39°F (4°C) and 130°F (54°C) where food-borne bacteria can grow most easily. Even though most of the potentially harmful bacteria will be killed by sous vide cooking, some can protect themselves from the heat by hibernating as dormant forms&mdashcalled spores&mdash that can blossom again given sufficient time and favorable temperatures.

To reduce the risk of food-borne illness when using the Cook-Chill-Hold method, follow these important guidelines:

  • Quick chill the warm cooking pouches of food fully submerged in an ice water bath (half ice and half water) for long enough to ensure a quick drop back to refrigerated temperature. Generally this will be the same length as the minimum time required to bring the food to temperature. Add ice or freezer packs as needed.
  • Immediately after chilling either refrigerate or freeze in the pouch.
  • Hold refrigerated pouches of sous vide cooked food for up to 5 days; properly frozen food pouches should remain safe for up to one year.
  • To ensure safety in holding, particularly with home refrigerators, be sure the refrigerator compartment maintains a temperature below 39°F (4°C), and that the freezer maintains a temperature below 0°F (-17°C).

End of cook book extract

To get more information on sous-vide cooking here