Vacuum drying

The name suggests it: vacuum drying is used to dry products using a vacuum - we use the process to turn delicious fruit into even more delicious fruit chips that are full of flavor and nutrients. But behind the principle of vacuum drying there is also a beautiful story that we definitely don't want to withhold from you.

The procedure was perfected in the 1930s by the pediatrician Dr. Marie Elise Kayser. Back then, vacuum devices already existed, but they were nothing more than toys for scientists. Dr. Kayser, on the other hand, saw more in these devices; namely a way to preserve breast milk.

She started experimenting and was successful. Using the vacuum, she removed the water from breast milk and thus produced the first milk powder. In 1936 she published her studies and made them accessible to the whole world. How many babies Dr. The number of times Kayser has saved his life to date cannot be counted.

Below we will show you how vacuum drying works today.

What is vacuum drying of food?

One of the most important physical laws of our universe ensures that vacuum drying works at all: the properties of a substance change under different environmental conditions, such as ambient temperature or pressure.

For example, at the bottom of the oceans, where there is extremely high pressure, there are thermal springs that emit water hotter than 300°. Of course, at these temperatures it would evaporate immediately on the surface.

In a vacuum, i.e. at very low pressure, the boiling point of water drops. It evaporates at low temperatures and heat, which would destroy vitamins and flavors, is completely avoided. For example, if you put an apple in a vacuum chamber, it will lose its liquid and almost automatically become a dried apple .

However, you have to pay meticulous attention to the temperature and pressure in the vacuum chamber. An incorrectly set value and the apple water may start to boil. Vacuum drying is absolute precision work.

Vacuum drying vs. freeze drying.

Wait a moment! Isn't that the same thing that happens with freeze drying?

Almost, because attentive readers will have noticed that the shock freezing step is not necessary with vacuum drying. In fact, the chest freezer was only invented 20 years after the vacuum chamber. Crazy, right?

This fact has an advantage: preserving food requires significantly less energy. Because what are the biggest energy guzzlers in your home? Probably the fridge and freezer – unless, of course, you have a sauna in the basement.

Not freezing has no effect on taste or nutritional content - but saving energy is of course a good thing for Mother Nature.

Vacuum doesn't always work.

However, vacuum drying is not suitable for every type of dry material. In order to motivate a product to release its water at low temperatures in a vacuum, it must have a particularly large surface area. The larger the surface, the easier it is for water to escape from the cells.

In practice, vacuum drying is therefore primarily used to dry powder-like substances such as plastic granules or medications. It's also pretty good for wood, because here it doesn't matter if it gets a little warmer - no one bites into a board and complains that it doesn't taste as good as it did fresh in the forest.

When it comes to food, vacuum drying is primarily used for grains and legumes, because a handful of rye is almost a very coarse powder.

Where we resort to vacuum drying.

You won’t find peas or corn here (yet). Nevertheless, we have left no stone unturned for you and our planet and have tried vacuum drying for many different types of fruit.

And lo and behold, with some fruits it actually works the way you and we want it to: wonderfully crunchy fruit chips come out of the vacuum chamber, which are rich in vitamins and minerals and still taste as if they had just been picked been.

For our dried organic apples, for example, vacuum drying works extremely well. We cut them into very thick slices, right across the apple, so that their surface is large enough to cooperate with our vacuum chamber.

What also characterizes the principle of vacuum drying.

Of course, vacuum drying - just like our other drying processes, freeze drying and air drying - works so gently that almost all of the aromas and nutrients in the dried fruit are retained.

When you crunch our vacuum-dried fruit soon, you can expect a real taste explosion. On the one hand, because the aromas intensify due to the lack of water. On the other hand, because we only harvest our fruits when they are completely ripe and only then dry them.

So they don't ripen in any dark containers, but rather develop their flavors in the sun until the last day. You are guaranteed to notice the difference immediately.

The last thing comes at the end.

Of course, the following also applies to our vacuum-dried fruit: Please store it in a place protected from light, preferably in an airtight package, and never expose it to moisture. Then it stays crunchy and delicious for months.

Why? Because vacuum drying is not the only drying process we use. But you probably already thought that when you read it. We also have freeze drying and air drying in our program, which we would also be happy to tell you more about.