F.A.Q. for future professional canners

What is pasteurization?
It is a process for food preservation by which a food is heated to a set temperature for a defined period of time before being cooled rapidly.

Pasteurization significantly reduces the number of microorganisms in the pasteurized product, but some pathogenic forms are resistant (such as spores). That's why it's important to keep pasteurized foods cool to prevent bacteria that haven't been destroyed from multiplying.
Pasteurization differs from the U.H.T. process used for milk processing where heat alone plays a role in the destruction of microorganisms.

What is sterilization?
It is a technique designed to eliminate any microbial germs from a preparation by bringing it to a high temperature (+ 100°C) for a defined period of time depending on the product being treated before being cooled quickly.

What is preserve?
Canning is a method of preserving food that consists of putting it in containers (cans or jars) that are made airtight and then heated to destroy contaminating microorganisms. The temperatures to be reached depending on the products manufactured are between 110 and 120°C.

Foods that can be canned at high temperatures include vegetables, meats, seafood, poultry and dairy products.
The only foods that can be canned in a boiling water bath are those that are naturally acidic, such as fruits, certain vegetables (e.g., pickles) or others that have had an acidifier (vinegar) added, or oil or alcohol.

A well-made can, by applying the appropriate scales to each product, allows a long-term preservation without refrigeration constraints, i.e. it can be stored at room temperature.

What is vacuuming?
It is a technique that reduces the amount of air and therefore the action of oxygen in a package.
It is not, by any means, a conservation technique; It should be considered - at best - as a method of extending the life of a fresh product in a refrigerated environment at a constant low temperature. Failure to comply with this provision could result in adverse health consequences.

Sterilization and pasteurization techniques:
The only formula accepted - in principle - by the hygiene services is the use of an autoclave sterilizer that complies with the current standards and is CE stamped.

What is an autoclave?
An autoclave is a thick-walled, hermetically sealed container designed to cook or sterilize under pressure (a few bars) with steam or water.
Autoclaving is a cycle of using an autoclave and autoclaving is the verb.

What is the mandatory equipment of an autoclave for the manufacture of canned goods?
The European Directive (PED 97/23/EC) requires that each device be equipped with:
- a reading thermometer
- a recording thermometer or other recording method to verify the sterilization cycle
- a pressure gauge to control the pressure
- a cooling system to immediately chill the can.

Autoclave Supply/Energy:
Our KORIMAT autoclaves can be supplied with electricity, gas or oil (for 240 liters)

We give you, as an indication, the consumption for each capacity:
(a) Korimat 120 litres:
- 380 three-phase - 9 kWh

(b) Korimat 240 litres:
- Natural gas: 3 m³/h - Liquefied gas: 1 m³/h
- Fuel oil: approx. 2 kg/h

Recurring checks:
Any owner of an autoclave must comply with the following controls:
- Every two years, interior and exterior inspection of the tank by a certified organization
- Every ten years, complete inspection and re-test by a certified body (otherwise, the operating permit may lapse)

Which form of energy should I choose?
You are, of course, free to choose your energy and we know that in some places there is sometimes only one possibility.
However, we would advise you to use electricity for several reasons:
- Ease of installation, much less stress than for gas and oil, no need for high and low ventilation
- No unwanted heat in the laboratory.
- Ability to program your device for nighttime use at a discounted rate.

Which autoclave capacity should I choose?
That is the question.
But the choice with us is limited, voluntarily.
4 capacities: 60 liters, 120 liters, 240 liters or 380 liters.

You need to determine how many jars to process at one time and their capacity.
In a 120-litre autoclave, you can, for example, sterilise:
- 110 x 250 g jars
- 45 x 950 g jars

In a 240-litre autoclave, you can, for example, sterilise:
- 220 x 250 g jars
- 90 x 950 g jars

What about sterilization scales?
Each can calls for a time/temperature scale. Give us a call and we'll discuss it with you.

Can you reheat a jar in the microwave?
As a general rule, no, ... but the Weck jar, without metal elements after sterilization, allows you to reheat your jar in the microwave without any worries: easy, time-saving, energy-saving! However, don't forget to open it before microwaving. 

How can I make sure my can is properly sterilized?
When a product is properly sterilized in a Weck jar, the outer tab is positioned downwards; It is a visual and effective phase to see at a glance whether your can is perfectly successful.

Any other questions?
Do not hesitate to call us, we will be happy to answer you.

Give us a call or send us an email at


F.A.Q. on Domestic Sterilization

How does home sterilization differ from professional sterilization?
Housewives generally do not have an autoclave sterilizer to make their preserves; She uses either an old-fashioned " washing machine " or a household sterilizer. With these devices, the maximum temperature reached is 100°C.
The determining factor for a good can will therefore be the sterilization time. It will be necessary to extend this time in order to destroy as many bacteria, fungi and microorganisms as possible.

How do I properly place jars in a home sterilizer?

It's very simple! Just follow the instructions in the drawing below:

Mode d'emploi des bocaux Weck

Whatprecautions should I take to make a good preserve?

First of all, good products!
Secondly, perfect hygiene. clean jars, lids and seals. 
Finally, respect the sterilization times.

Can everything be sterilized?
Yes: meat, game, pâtés, rillettes, game, foie gras, vegetables, fruit, soups, compotes, jams and even cakes...

Do jars need to be "sterilized" before a product sterilization cycle?
NO! This is a heresy that has been conveyed for a very long time in " grandma's " recipes; A little thought leads you to see that the jars do not have to undergo sterilization before being filled. Even so, it would be useless, because the moment they are taken out of the hot water, and placed on a kitchen table, they are no longer sterile!
They just need to be clean; Simply wash them in lukewarm water with any household product, wipe them down: they are ready to be used again. Once filled, the jars will be sterilized along with their contents.

Can you use any type of jar?
Yes, of course as long as it is a jar intended for sterilization; Jars reserved for decoration should not be used for food use. If you reuse a jar, the seal (or if applicable, the capsule) must be absolutely new. 

Should you boil empty jars before sterilization?
No! This is a common misconception that we often see on the internet. You just have to wash them well. Your jars and seals should be clean and dry. Since once full, you will sometimes even scald them for more than an hour, it is completely useless to sterilize them beforehand. They will sterilize at the same time as the food in them!
If you sterilize your empty jars, your environment is not sterile (neither your hands, nor your kitchen, nor your tea towel), this process will have been useless, because recontamination will then be immediate. It's a waste of time and energy.

Should you boil jar seals?
No, in principle, unless the manufacturer specifically states that it must appear on the packaging. In the case of Weck seals, they are made of natural rubber and should not be boiled before sterilization. The gaskets are not reusable, nor are the capsules , which must be changed every time they are sterilized. Each brand of jars sells the right gaskets for the jar. So, Weck gaskets ONLY go on Weck jars.
If you use other brands of jars such as Mason, or Le Parfait, strictly refer to the rules recommended by these brands. 

Can jars be reused?
Of course! This can be done as long as the seal or cap is changed, and the jar has no impact or cracks.

stérilisation domestique WECKShould jars be allowed to cool with sterilization water?
NO, never ; This is also a misconception; The principle of sterilization consists of a smooth temperature rise, a sterilization step and rapid cooling; The jars should therefore be removed from hot water immediately at the end of the sterilization process and, if possible, cooled with a jet of fresh water; The sooner they cool, the better they will keep.
If you let your jars cool in water, there will be a re-growth of bacteria in the water.  

How do you make sure a can is successful?
When the jar is cooled, do a test by trying to open the lid; The latter must put up a natural resistance. In the case of WECK jars, the tongue naturally leans downwards after sterilization of the jar. If the seal tab is rising upwards, sterilization was not successful. It is therefore necessary to store this jar in the fridge and eat its contents in a very short time.

Can botulism be prevented by using a household sterilizer?
Obviously! Botulism is caused by a bacterium that is destroyed at high temperatures (from 80°/90°).
If, therefore, you rigorously apply the sterilization scales communicated to you, you will have no problem.

sterilisateur ménager weck

What is botulism and Clostridium botulinum?
Clostridium botulinum is a bacterium that  causes botulism. Clostridium botulinum is a spore-producing bacterium that represents the resistance form of the bacteria. This spore can withstand weak heat treatments (e.g. pasteurization) and germinate (i.e. give a metabolically active cell) which can pose food safety problems.
It secretes one of the most potent toxins in the animal world. Activated by ingestion, this toxin then diffuses in the body and acts by blocking intermuscular transmission: it inhibits the motor neurons of muscle contraction. The toxin is then said to cause flaccid generalized paralysis (unlike tetanus toxin which inhibits neurons that inhibit muscle contraction, thus inducing spastic generalized paralysis). This infection can lead to death from paralysis of the respiratory muscles if no treatment is put in place. There are three forms of human botulism: foodborne botulism (ingestion of the pre-formed toxin in the food), infant botulism (colonization of the gut by the bacteria) and wound botulism. Poisoning often follows the consumption of poorly sterilized canned goods or "homemade" ham and cured meat. The toxin is heat-labile and a simple boiling is enough to prevent the risks.
The toxin is resistant to gastric acidity but is heat-labile (destroyed at around 80 to 90 °C): the result is that if a suspicious food is heated to a boil just before consumption, all danger disappears.
We therefore warn you against the "advice"  given on certain foreign sites, mainly Canadian and American, which recommend the mandatory use of an autoclave pressure pot to escape botulism;
These devices do not comply with EEC or NF standards. Thus, you remain responsible for the purchase and use of them. If you choose to purchase this type of product outside the EEC, we strongly encourage you to follow the manufacturer's advice and recommendations. 
For these reasons, MCM Emballages has chosen not to market this type of device, preferring to stick to EEC brands. 
These small Presto, or All American, devices are in common use in North America. Don't hesitate to check with the seller before  buying. 
(By definition, in France, an "autoclave" refers to a device reserved for industrial and professional use. Designations and standards vary by country.)

If you want to invest in an equipped electrical appliance, a household sterilizer from Weck or another brand is perfect! If you don't can, it's not necessarily worth investing in this type of appliance. For home sterilization, all you need is a large pot and a cook's thermometer.

How to find out more?
By contacting us at téléphone mcm emballages, or

Rely on the professionals whose job it has been to preserve for more than 25 years!


See you soon.
The MCM Emballages Team