What happens when boiling down?
When boiling down, fruit, jams, pickled vegetables but also sauces and chutneys are preserved in the glass. So you save the taste of summer into the cold season and can fill up your storage cupboards with everything you have harvested in summer and what you simply do not want to do without in winter. This is not only interesting for self-catering.
Basically, it is possible to boil a wide variety of foods – from fruits and vegetables to cakes and bread to pastries. The most common method is boiling down in a water bath. This kills the microorganisms that are responsible for the putrefaction process and squeezes the air out of the glass, creating a vacuum that leaves microorganisms with no chance. The food is preserved with its full aroma over a long period of time. Also possible: canning in the oven.
What foods can I boil down?
Suitable for boiling down are:
- all types of fruit
- any kind of vegetable
- Stews and soups
- Meat (for advanced!)
However, you should refrain from boiling down:
How it boils down – step by step
No matter what you want to can: The principle of the water bath is the same everywhere.
1. Cooking
First prepare the food you want to boil down. You can find recipes for jams and chutneys with us and we will also show you great ideas for boiling fruit.
2. Prepare mason jars
For boiling down you need preserving jars in different sizes with rubber rings and spring clips (classic Wake-up glasses, optionally also go Screw glasses with separate screw ring and a cover that can be placed on, or Twist-off glasses), an automatic saucepan, a saucepan or a large saucepan with a tightly fitting lid. Also: an inlay grid (possibly a cake rack) and several dampened kitchen towels and – importantly – a thermometer!
Careful preparation of the mason jars is essential for the process to be a success. It is best to use classic jar glasses with a rubber ring and clips. They close particularly well.
Before boiling down they have to Preserving jars are sterilized, i.e. freed from germs. It is not enough to simply rinse the glasses hot. Even the dishwasher is not enough, because the water needs a temperature of 100 ° C. It is best to bring a large pot of water to a boil and let the jars and lids sterilize in the bubbling water for a few minutes.
If you don't want that, you can also use the Weck glasses Place in the 140 ° C hot oven for 10 minuteswhile the lids are cooking separately in a small saucepan. Boil the rubber rings only briefly (approx. 3 minutes) in a saucepan with a little vinegar.
Then place the preserving jars on a tea towel that you have moistened with warm water. This way you reduce the risk of the glasses shattering when you fill in the food.
3. Fill glasses
It is best to fill the preheated glasses with a funnel so that nothing goes wrong. Leave as little space for air as possible by filling the glasses up to about 2 cm below the rim with food. (Exception: If you put dough in the jars, you should only fill them half full because the dough is still rising). Small spills on the edge must be wiped off.
Close the jars immediately after filling.
4. Boil glasses in a water bath
Now we finally come to the actual boiling down. The principle: The glasses are placed in a large saucepan (preferably in a saucepan) and stacked if necessary and then covered with water. It is important that the glasses do not stand directly on the bottom of the pot. Put a tea towel or a cake rack on the floor beforehand and place the mason jars on top.
Now fill in the water and heat it up. Ideally, the water has a temperature similar to the content of the glasses. Then the glass is less likely to crack. The cooking time specified in the recipe starts as soon as in the Glass bubbles rise and the contents boil gently.
With a kitchen thermometer Water temperature check and ensure that it matches the temperature required in the recipe. If necessary, add water if too much of it evaporates. The Preserving time note!
5. Boil down the glasses in the oven
The glasses must also be in the water in the oven. To do this, place the preserving jars (again on a dish towel!) In a drip pan or on a deep tray and add approx. 2 cm of water.
Set the oven to 175 ° C and watch the glasses. As soon as air bubbles rise in the jars, the contents of the jars boil – and the boiling time specified in the recipe begins.
There are differences depending on the content of the glasses:
- When you boil fruit, you can now switch off the oven. Leave the glasses in the water and in the oven for another 30 minutes.
- With vegetables first reduce the temperature to 150 ° C and then leave it in the oven for 90 minutes. Only then switch off the oven and leave the glasses in the water and oven for another 30 minutes before you remove them.
6. Lid sample
After boiling down, take the glasses (preferably with a glass lifter) out of the pot or out of the oven and let them cool on damp tea towels. Leave the clips on the mason jars so that the vacuum can form.
You can tell from the lid test whether the boiling was successful and whether a vacuum has developed in the glass. After the complete cooling, the brackets of the Wake-up glasses loosen and touch the glass on the lid. If you lift it up a little now, the jar has to sit firmly on the lid. Only then is the vacuum safe.
At Twist-off glasses or screw-on glasses you can recognize the success by whether the lid bulges inwards. In addition, the vacuum is often noticeable by a loud pop of the lid. The noise is generated when the lid – drawn in by the vacuum – pulls inwards into the screw-top jars. Then everything is fine.
Difference between boiling down and bottling hot
Incidentally, it is not the same whether you fill food (e.g. jam) in jars hot or whether you boil it properly. The difference is that the glasses do not stand in bubbling boiling water again afterwards and the bacteria are not killed in this way. This procedure is only safe if the bottled food is one high sugar or acidity like jam, compote or tomato sauce.
Jars for jams, jellies, chutneys and compotes do not necessarily have to be sterilized – but of course they have to be absolutely clean! It is best to boil briefly after washing in a large saucepan with boiling water. Then take it out with tongs and let it drip upside down on clean tea towels.
How long is the cooked food stable?
Raw jam does not last long in the glass. If you want to keep them longer, you can freeze them. You can keep home-made jams and jellies for up to two years. Preserved fruit and vegetables can be kept for up to a year.
You should definitely store preserves in a cool, dark and dry place. In between, check regularly whether the jars are still tightly closed. If not, gases have formed and the lid has been pushed up. The content is then spoiled and can no longer be eaten!
If the jam starts to mold, which is made in equal parts from sugar and fruit, you can remove the moldy area generously.
Do you feel like waking up now? Then become a self-sufficient (at least partially) this year! You will see: Everything you have cooked yourself with regional and seasonal food tastes just as good in winter.