Vacuum bags: which should I choose? - Sous Vide Cooking

When it comes to vacuum packing, one of the most frequent questions relates to which vacuum bag to choose. How do I know what each type of vacuum bag used should be for? In this post we are going to talk about the different types of vacuum bag and explain what each of them is used for.

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The importance of choosing the right vacuum bag

As our corporate chef Enrique Fleischmann, an expert in vacuum and low-temperature cooking, explains, the first thing to understand is that not all vacuum bags can be used for everything. That is why you have to know how to pick a vacuum bag that is going to work with the elements you are using. In addition, you need to consider that, even if you are not a specialist in plastics, the company that supplies the bags will have done all the necessary tests and should be able to provide a technical sheet with all the information. It is important to think about acidity, salinity, freezing temperature, exposure temperature and time, etc. so that above all we understand that a plastic bag, if subjected to heat or cold, could end up migrating to the food. This means that the bag, at a given moment, could lose its original characteristics with the danger that these migrations could stick to the packaged food.

Types of vacuum bag

We have different vacuum bags that vary in terms of the thickness of the bag and the proportion of polyamide and polyethylene.

• Conservation bags: these are vacuum bags in which conservation is vital. They are ideal for packaging and storing both fresh and cooked products. Most of them can also be used for pasteurisations, or in other words, for cooking up to 80 degrees.
  However, not all of them are suitable for cooking at more than 80ºC or for freezing.  It is important to check whether the bags can be used for cooking and/or freezing since if the temperature is exceeded it could result in the plastic degrading. Normally, bags for cooking and freezing are very similar to conservation bags, but they are normally firmer and thicker. These are normally suitable for cooking up to 120ºC and for freezing down to -21ºC. For cooking at temperatures above 120ºC you will need to use metallic bags, which are discussed later.

• Shrink bags: shrink bags can be used to retain the shape of the packaged product. While they appear to be very thin bags, when they are subjected to heat they contract and become very hard, “sticking” to the product more. They are particularly suitable when you want to emphasise the shape of the product, such as with a leg of ham, and they are also particularly suitable for conserving juices within the bag. They are used above all for meat and cheese products.

• Metallic bags: metallic bags a relaminated vacuum bags that can withstand a large amount of pressure and better retain the characteristics of the packaged product. In addition, since no light can enter the bag, the products do not lose their organoleptic quality to the eye. These bags are normally used in the food industry. There are two types of metallic bag, one where both parts are metallic and a second where the back is metallic and the front is plastic. These are normally used to make the product look more attractive. For example, with packaged cold meats. Metallic bags are used when cooking at more than 120ºC, since they are thicker and their structure is fully resistant to pressure without losing its original qualities.

Important: not all vacuum packing machines can seal this type of bag. Check that your machine can work with these bags. For example, we have Sensor Ultra vacuum packing machine models that can seal these bags.

• Compostable bags: increasing numbers of suppliers are trying to find a solution to the problem of the use of plastic. Although all the other bags mentioned in this report can be recycled, they rely on people doing this. Compostable bags go one step further and do not use plastic in their composition. However, these bags do not handle temperatures very well since there is degradation at both high and low temperatures. Nor are they very good with humidity. That is why they are not suitable for freezing and they only allow for cooking up to temperatures of 85ºC for twelve hours at most. They are a very good option for conserving fresh products and/or dishes that do not need to be heated or regenerated.  

Important: many suppliers are working in this area and there are biodegradable bags that can be used at other temperatures and for different exposure times.

Other packaging options

• Heat-sealed trays: there are two types of heat-sealed tray. First, the most common are the trays into which the cooked product is placed before being heat-sealed, but there is no vacuum inside. Second, there are trays with a vacuum inside that need more sophisticated machinery, which does the same process as before but halfway through a chamber generates a vacuum and then directly covers it with plastic.

Important: remember that trays are not normally a very good option for vacuum cooking since they tend to float.

What is a vacuum packing machine?

A vacuum packing machine is a device that removes the air from inside a plastic bag containing food before hermetically sealing it. The main aim is to preserve food by preventing the growth of bacteria and slowing down spoilage.

Why use a vacuum packing machine to preserve food?

Using a vacuum packing machine considerably extends the shelf life (3 to 5 times) of foodstuffs without altering their taste, nutritional qualities or fresh appearance. This prevents mold and oxidation, and reduces food waste.

How to choose your vacuum packing machine?

To choose your sous vide machine, you can take into account :

• Your use: occasional or frequent.
• Your desired features: manual/automatic vacuuming, multiple sealing, etc.
• Your budget
• The size of the product, depending on the space you have available.

Do I need specific accessories to use a vacuum sealer?

You'll need vacuum bags or rollers adapted to your machine model to properly vacuum pack your food product.

Are vacuum bags reusable?

Some vacuum bags can be reused several times, especially if the food they contained was clean and low-odour. However, it' s best to use a new bag if you have any doubts about the cleanliness of the previous one.

Is it possible to vacuum-pack gastronorm containers?

Yes, some sous-vide machines alsooffer an accessory for vacuum-packing directly into gastronorm trays without having to use a bag.

What is the shelf life of vacuum-packed food?

Shelf life varies according to the type of food:

• Raw meat and fish: up to 2 weeks.
• Fruit: up to 3 weeks.
• Vegetables: up to 4 weeks. It may also depend on the initial freshness of the food, as well as storage conditions (refrigerator or freezer).

Are there any health risks associated with vacuum packing machines?

No, as long as you use your machine correctly, following the manufacturer's instructions and complying with health standards (regular cleaning, proper use). The risk exists mainly when using a machine in poor condition or with incompatible accessories.

Can I cook my food in a vacuum bag?

Vacuum-packed food can be cooked at low temperatures (between 50°C and 90°C) using sous-vide cooking, which ensures even cooking and preserves the food's nutrients. Make sure that the bags used for this technique are heat-resistant.

Can all types of food be vacuum packed?

Yes, almost any type of food can be vacuum packed, including meat, vegetables, fruit and even certain liquid products such as soups and sauces, provided they have been chilled beforehand.

Can salads and raw vegetables be vacuum-packed?

Yes, salads and raw vegetables can be vacuum-packed to prolong their freshness. However, care must be taken not to crush fragile vegetables during air suction.

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Can I vacuum-pack hot products?

No, it is not recommended to pack hot products, as this can encourage bacterial proliferation. It is advisable to cool food before vacuum packing.

Is it possible to vacuum-pack a sauce dish such as blanquette de veau?

Yes, dishes in sauce can be vacuum-packed, provided the sauce has been chilled beforehand to avoid any temperature-related risks.

Does a product that needs to be kept cool need to be kept cool after vacuum packing?

Yes, a product that should normally be kept refrigerated should always be kept refrigerated even after vacuum-packing, to ensure optimum preservation.

Can vacuum-packed food be kept at room temperature?

This depends on the type of food in the bag. Some non-perishable foods, such as nuts or certain cereals, can be stored at room temperature, but most should be kept in a cool place.

Is there an official list of best-before dates for all products?

No, there is no official list, as shelf life depends largely on storage conditions and the type and freshness of the food. We do, however, advise you to respect the best-before dates generally encountered for each category of food.

What is protective atmosphere or M.A.P?

Modified Atmosphere Packaging (MAP) is a process which consists of modifying the internal atmosphere of the packaging by adding or removing gases such as oxygen, carbon dioxide and/or nitrogen to further extend shelf life.

How to choose the right vacuum bag size?

To choose the right bag size: measure the length and width of the product to be packaged, and add around 10 cm in height to allow sufficient space between the top edge of the product and that of the bag to facilitate hermetic sealing.

What bag thicknesses are required?

Common bag thicknesses range from 60 microns to 200 microns, depending on the application:

• For domestic use with low suction, prefer bags between 60 and 90 microns.
• For professional use or with larger food items, opt for bags between 100 and 200 microns.

Do vacuum machines need servicing?

Yes, an annual service is recommended to keep the machine running smoothly, especially if it is used frequently. In case of intensive use (daily use of more than 4 hours), a half-yearly overhaul is recommended. This maintenance must be carried out by a qualified professional

Can I carry out maintenance without the intervention of a professional?

Yes, after each use, clean the bell and cover with a damp cloth. Every week, check the oil level and top it up if necessary.

Can I use detergents/solvents to clean the machine?

Avoid aggressive detergents and solvents, which can damage parts of the machine. Use only cleaning products specified by the manufacturer.

When should I add oil to the pump?

Consult the manufacturer's operating manual to find out when to add oil to the pump at the recommended intervals. Generally speaking, it is advisable to add oil to the pump every month. Check your oil level and, if necessary, add a little at a time, up to the maximum permitted limit.

When should I change the oil in my pump?

The oil should be changed according to the manufacturer's instructions, generally every 6 to 12 months, depending on the use of your machine.

When should I change the pump oil filter?

We recommend changing the filter every 6 months and after every oil change. Follow the manufacturer's recommendations.

When and how to maintain the sealing bar?

To maintain your sealing bar: Unplug your unit, regularly check its cleanliness, gently wipe with a soft cloth, and replace damaged parts according to the manufacturer's instructions.

How do I replace the silicone seal on the sealing bar?

Follow the manufacturer's instructions to remove the old silicone seal and install the new one correctly.

How do I replace the cover gasket?

The cover gasket must also be replaced in accordance with the manufacturer's instructions to avoid sealing problems.

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