BRIEFLY EXPLAINED - Throw away less: how to keep fruit and vegetables edible for longer

Reader question: How can I store fruit and vegetables for as long as possible? What role does the choice of variety and the type of storage play?

It happens particularly quickly with raspberries: mold spreads. But how can you prevent fruit and vegetables from spoiling quickly? It depends on whether a food is at risk of spoiling for physical, chemical or microbiological reasons. If we drop an apple on the ground, it gets a bruise that turns brown. First physics, then chemistry, comes into play here. The only thing that helps against this is to be careful and prevent bruises when storing fruit and vegetables.

But the most common cause of spoilage is microbiological spoilage. "Fruit and vegetables always contain bacteria and fungi," says Giovanna Spielmann-Prada from the research group for food microbiology at the Zurich University of Applied Sciences (ZHAW). How quickly this happens depends on certain properties of the food. The higher the water content, the faster it goes bad.

Storage is also crucial. Every food has its own comfortable climate. This applies above all to temperature, humidity and brightness. Many types of fruit and vegetables like to be kept cool and protected from light - so the drawer in the lower part of the refrigerator is the right place for them. Conversely, tomatoes, onions and bananas should be kept at room temperature in the kitchen. Potatoes and apples are best stored in the cellar, protected from light. If you are unsure about the best way to store a certain food, you can find helpful information from consumer protection agencies .

Berries and citrus fruits are among the fastest-perishing foods. They are particularly susceptible to mold and also contain a lot of water. The rule here is: consume as quickly as possible after purchase. Foods such as apples, pumpkins and potatoes are much easier to care for. They can be kept for weeks. The harder the skin of a product, the longer it will last.

Hardly any pesticides or wax coatings are used in organic farming. However, according to Claudio Beretta from the Food Technology Research Group at the ZHAW, there has been little scientific research into whether organic products therefore have a shorter shelf life than conventionally grown ones.

What is clear, however, is that the shelf life also depends on the variety. For example, Boskoop, Idared and Topaz are typical storage varieties with a long shelf life. There are also varieties of potatoes and carrots that have a longer shelf life. In recent decades, agricultural research has deliberately developed varieties that are more resistant to mold, fungi and mechanical damage. However, from Beretta's point of view, this has sometimes been at the expense of taste and nutritional content - for example tomatoes.

Packaging also plays an important role. "Everything has its advantages and disadvantages," says Giovanna Spielmann-Prada. The plastic covering around the broccoli in the vegetable display protects it from germs on the customer's hands. At the same time, however, the plastic retains moisture, which encourages mold growth. It is therefore best to take the food out of the plastic packaging in which it was packed in the store. Intelligent packaging, which is currently being researched, is intended to make food last longer in the future. For example, by making it breathable or slowing down ripening.

To avoid accidentally having spoiled food on your plate, you should check it regularly. This can also prevent mold from getting onto other fruits or vegetables. The higher the water content of a food, the more careful you should be and throw it away if it looks, smells or tastes suspicious.

And there is more you can do than just pay attention to storage. For Spielmann-Prada, it is important to buy regionally produced food that is as seasonal as possible. Because the longer the transport route, the older the food is by the time it ends up in our shopping basket.

At home, the motto should be "first in, first out": what goes into the fridge first should also be used first. "It's best to make a plan of what you want to eat in the coming days and only buy the corresponding foods. You should also pay attention to their shelf life," says Spielmann-Prada. Planning is even more important the less often you shop. If you only do this once a week, you shouldn't plan your berry feast for the end of the shopping week. If you buy supplies from the store every day, you don't have to pay as much attention to shelf life.

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