More energy efficient than the freezer, you chose to make preserves in jars and you finally decided to taste them. But as always, it is the tragedy… your preserves in jars are failed and are not edible!
The basic principle of canning? The sterilization of food combined with the use of an airtight jar after heat treatment to avoid any appearance of microorganisms that can be harmful to your health.
Botulinum toxin: why your canned food ferments and is no longer edible
The aim is to prevent the proliferation of microorganisms and in particular that of the very powerful botulinum toxin which can be found in many products. This toxin produced is responsible for botulism , a disease that can lead to paralysis and respiratory failure which can be fatal.
To limit the spread of microorganisms and the production of toxins as much as possible, it is therefore imperative to follow these tips to the letter to prevent your jars from fermenting.
You will have understood it, rigor is required to prevent your preserves in jars from fermenting
Steps to follow to avoid jars that ferment
1. Choose the right recipe
We recommend that you first choose your recipe. Preserves are demanding and leave no room for improvisation. Choose a recipe specific to homemade preserves in jars. It should include heat treatment times, jar size and air space to be left during filling, which are specific to each preparation.
2. Choosing the right jars
Use jars specially made for canning.
There are 2 types of closures:
- To screw , consisting of a capsule and a metal ring.
- With a gasket.
The capsule or the seal must be changed each time you use it. You can, however, reuse the metal ring and the pot several times, if they show no signs of wear or dirt.
There are 2 types of jars:
- Jars with straight walls: to be chosen preferably for your solid preparations, which contain few liquids, because they will be easier to unmold;
- Jars with rounded walls: to choose for liquid preparations.
3. Work in a clean environment and impeccable hygiene: the key to avoiding fermenting cans
Once your worktop, utensils and hands are clean, start by washing your jars, lids and rubber rings in hot water and soap.
Then immerse them in a pot of boiling water and maintain the temperature at 100 ° C for 10 min. Let the jars dry upside down and in the open air on a clean tea towel. Do not dry them especially so as not to contaminate the pots.
4. Prepare the recipe
Meanwhile, it's time to prepare your recipe.
Make sure you have the correct pH
Let us not forget the particular case of the tomato whose pH varies between 4.0 and 4.7. To prevent bacteria from developing, we recommend that you add bottled lemon juice or citric acid to your tomato preparations. You can then treat them with boiling water.
Why specifically bottled lemon juice? Using bottled lemon juice allows you to have a pH value of the juice that is uniform, while fresh lemon juice has a pH that will vary and is therefore random.
Follow the recipe carefully to prevent the jars from fermenting
Whether it's the quantities, the ingredients, the size of the jars or the sterilization time: no room for improvisation, scrupulously respects the recipe:
- Modifying an ingredient or its quantity would lead to changing the pH of the mixture (that is to say, its acidity), and therefore to promote the possible proliferation of toxins which would lead to preserves which ferment;
- Failure to respect the size of the jars could modify the sterilization conditions and therefore lead to fermentation of your can.
Preparation tips for preserves in jars that no longer ferment:
- Use only very fresh products and especially never frozen ingredients ;
- Hollow out the poultry and wash them in water;
- Separate the peelings and waste from your food to minimize the risk of contamination of your products. Use, for example, a cutting board to peel and a different one to cut. To prevent the proliferation of bacteria on the boards, you can also put them in the refrigerator once cleaned. Rather favors plastic boards than wooden ones, which are less hygienic;
- Most vegetables will need to be blanched or even peeled for successful canning. Indeed, blanching will inactivate the enzymes (proteins which are intended to accelerate chemical reactions) present in the vegetables, and consequently to prevent your superb preserves in jars from fermenting.
5. Fill the jars
Once your recipe is complete and the rules have been followed to keep your jars from fermenting, it's time to fill your jars.
The pots should be filled when the food is hot.
To avoid dirtying the rim of your jars, you can use a jar funnel, it will allow you not to dirty your jars and thus prevent your jars from fermenting as much as possible.
The presence of residues on the edge of the jar could promote the fermentation of your preserves in jars. Clean it well in the opposite case.
To ensure there is air between the food and your lid, be careful not to fill your pot to the top. There must indeed remain a free space between your preparation and the top of the pot. Follow the directions in the recipe. We speak in general, between 0.5 and 2 cm depending on the food. Some pots have marks to show you the limit to be observed.
Removes any air bubbles, along the sides and between the ingredients using a spatula to prevent them from rising to the surface and thus modify the amount of air between the preparation and the lid.
If you have chosen to use screw-in jars, be careful not to over-tighten the metal ring, this may prevent steam from escaping during heat treatment.
6. Apply heat treatment
If you are using a jar with a rubber seal, you will need to boil it before using it to seal the jar.
Boiling water sterilization
This step concerns the most acidic preparations: fruit in syrup, marmalades, jams, fruit juice, etc.
- Place a tea towel at the bottom of your pot to prevent your pots from touching and being damaged during sterilization;
- Immerse the closed jars in the pot filled with water, making sure they are covered with 3 cm of water;
- Bring the water to a boil, and start counting down the heat treatment time from the moment the water boils (100 ° C);
- Maintain the water at 100 ° C for the duration of the treatment indicated in the recipe;
- Once the heat treatment is complete, allow the water to cool and do not remove the jars until the water is cold.
Pressure sterilization
This step concerns the least acidic preserves: vegetables, meats, seafood, dishes in sauce, soups, soups, etc.
- Place a tea towel at the bottom of your pot to prevent your pots from touching and being damaged during sterilization;
- Fill the pressure cooker with water, following the manufacturer's instructions;
- Close the pressure cooker with the lid and lock;
- Count the heat treatment time from the moment the valve whistles;
- Once the heat treatment is complete, allow the water to cool and do not remove the jars until the water is cold.
7. Check that the jars are properly closed.
With jars with rubber seals : Try to lift the lid without touching the seal.
With metal ring jars : Once the heat treatment is finished, you can remove the metal ring. The lid should adhere to the jar.
If they are not properly closed, the heat treatment step will have to be started again. In particular, this can be the consequence of reuse or contamination of the seal or cover, failure to comply with the filling limit or the heat treatment time.
8. Store the products properly
Now that you have filled your jars by following our advice to prevent canned preserves from fermenting, it's time to store them in a cool, dark place.
Before leaving them, don't forget to stick a pretty label with the date of preparation and the name of the recipe on your super jars.
9. Make sure the can has not fermented
Before enjoying your delicious can, you will have to verify that your can is a success and that it is therefore edible.
What are the signs of fermentation in my jars?
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Traces of fermentation inside the lid;
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A swollen cover;
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A damaged pot;
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A bad smell that emanates from the pot.
If your can shows one of these signs, it will unfortunately be necessary to part with it and especially not to eat it.
We advise you to consume your jars within 10 to 12 months, even if they should, theoretically, stay good longer if they do not show signs of wear and that you have followed our advice to prevent the preserves in jars. do not ferment!
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