Foods: Conservation - Drying

Not so long ago, our grandparents preserved their produce (fruits, herbs, meat, mushrooms…) themselves. Why? People had to keep the food edible over the winter. The meat was smoked, jams or compotes were made, pears were dried. In those days the supply of goods was not as good as today and refrigerators and freezers were way too expensive.

But why does food rot?

• External conditions, e.g.: very low temperatures, strong solar irradiation...
• Microbiological decay: Tiny organisms (micro-organisms) like bacteria and fungi settle on the surface of the food, 'nibble' at it and may render the food inedible. However, they need water to survive, which they withdraw from the food, e.g. the bread. The picture shows moulds seen through a microscope.
• Certain chemical substances (enzymes) in the food itself cause the decay of foods and make them inedible after a certain time (e.g. rancid fat). These substances only have an effect if enough water is present.

ATTENTION: Never, ever eat rotten or mouldy foods! Mouldy bread has to be thrown away altogether, even if only a part is mouldy, as moulds are able to produce toxins, which spread to the part that was not contaminated as well!

A simple way to preserve foods - the way our ancestors did it simply and efficiently - is to withdraw the water from the food by drying. Thus, the microorganisms lack the water necessary for their survival and the enzymes loose their effectiveness. But remember to store the food in a dry place afterwards, otherwise everything would have been in vain.

How do you dry foods?

There are several ways to dry foods and the simplest are:

• Drying with warm air = air-drying, e.g.: herbs, spices, tea, mushrooms...;
• Parching = drying in the oven with hot air, e. g.: fruits and vegetables
• Drying on hot rolls or by dispersing in hot air, e.g.: eggs, pasta, dried milk, ...

The disadvantage of drying food is the fact that vitamins are destroyed, and fruits discolour or taste different afterwards.

Water can not only be removed from foods by drying, but also with substances that attract and bind the water like salt or sugar. Examples: sugared jam, salted fish.

Of course there are numerous other methods to preserve food like deep-freezing, cooling, heating (pasteurising, sterilising), irradiating, adding preservatives, airtight packaging, etc.

However, fresh and untreated foods (vegetables, fruits...) like a freshly picked apple or a juicy carrot directly from the garden are still the healthiest choice since they have the highest nutritive value.