Preserving food: free­zing vegetables & more

Prioritise seasonal and regional

Fresh foods are indeed the best choice, provided they are seasonal and from the local region. After all, we can then be sure that the fruits and vegetables are freshly harvested and didn’t spend long on the road and in storage. This ensures that as many vitamins and minerals as possible are retained. But it’s not always possible to go to a market or a local farmer's shop. Are there any healthy alternatives?

Extending the shelf-life of vegetables

Preservation is the key word. This means extending a food’s shelf life by slowing down the natural decomposition processes. Depending on the preservation method, nutrients either get lost or else, in some cases, remain or even improve. But that’s not everything: this is also a way of reducing food waste.

From the freezer: a good alternative

If you don't have access to freshly harvested vegetables, a healthy alternative is the frozen version. The foods are harvested ripe, at maximum nutrient density, partially blanched and then directly shock-frozen. Temperatures of minus 30 to 50 degrees interrupt the enzymatic degradation processes, yet the vegetables retain their valuable substances and a large part of their cell structure.

Vitamin C content is quickly lost

Green beans and spinach in particular are often better from the freezer than fresh, because the vitamin C they contain is very sensitive. If fresh spinach is stored at room temperature for 24-48 hours, it already loses over 50% of its vitamin C content. The difference between frozen spinach and spinach from the fridge harvested ten days ago is even more evident. Here, frozen produce is clearly superior to fresh. Other advantages include the long shelf life, portioning and availability of seasonal products.

In the end, if you’re not sure when shopping whether you’ll be using those fresh beans in the next few days, feel free to go for the frozen variety.  

How long do frozen foods last?

Vegetables, fruits and berries can be stored in the freezer for up to a year. By contrast, meat, poultry, seafood and baked goods should be defrosted and eaten from between 3 to 6 months.

Fermented – Grandma knows what’s good

Fermentation is used not only to preserve food, but also to change its taste. Triggered by different micro-organisms (bacteria, yeast or mould), the method was used by our grandmothers’ generation to preserve all kinds of food. Fermented foods that we should be eating:

• sour dough bread
• yoghurt
• sauerkraut
• kimchi
• kefir
  

In the fermentation process, most foods form probiotics – good micro-organisms like bacteria and fungi – which protect our gut flora and health.

How long do fermented foods last?

Depending on the food and preferred level of fermentation, the process takes from a few days to several weeks. Firmly sealed and stored in a cool, dark place, fermented foods last 1-2 months.

Dried foods

The drying process extracts water from the foods, which deprives bacteria and fungi of their breeding ground. Minerals and many of the vitamins remain intact in this method. At the same time, the dehydration process concentrates the nutrients. This means that 100g of dried fruits, for example, contain more potassium, iron and magnesium than 100g of fresh fruits. But be careful: the same goes for the fructose and therefore calories. For this reason, eat dried fruit in moderation.

How long do dried or desiccated foods last?

Sealed in airtight packaging, dried or desiccated foods can be kept for up to 6 months. Cool and dark storage is ideal here, too.

Better than nothing: canned

The advantage of canned goods is that they can be kept for years. But that’s where the benefits end. Canned food loses a lot of its nutrients compared to frozen and fresh food. In order to preserve the food, it is usually heated twice, which is where most of the water-soluble vitamins are lost. This isn't a problem when it comes to pulses like chickpeas, lentils and beans, as these are cooked anyway before being eaten.

Preserving foods: a summer feeling in winter too

Preserving involves putting pre-boiled food – mainly fruit or vegetables – into jars and sealing them with a lid with a rubber ring. The jars are then heated in a bain marie to 60 degrees which kills off all bacteria. If the temperature in the bain marie is more than 100 degrees, all micro-organisms are also destroyed. This makes the food last even longer – but at the expense of vitamins and nutrients.

How long do preserved foods last?

Stored in a cool, dark and dry place, the foods last for several years. The usual rule applies: get rid of any foods that smell or look dubious.

Pickling: gherkins and fruits with alcohol

Alcohol and vinegar act as preserving agents by penetrating the food completely and replacing its natural liquid. Alcohol kills micro-organisms, while the diluted acetic acid in vinegar prevents their growth. Pickling involves completely covering food – raw or cooked – with white wine vinegar or rum, for example, and sealing it airtight.

How long do pickled foods last?

Stored in a dark and cool place, they will last for several months. The basic rule is: pickled foods should be destroyed if they change colour or smell, if bubbles form, or if the seal breaks.