Bärn Kit BlogApps · art · saving food – in Bern
Saving & sharing food

Storing and reheating leftovers safely

Yesterday's leftovers make a good meal today. They stay safe if you cool them quickly, keep them cold, eat them soon and get them properly hot when you reheat them.

By Richard Červenka · 6 min read · updated 4 November 2026

Typographic card with the title “Reste sicher aufbewahren und aufwärmen” (storing and reheating leftovers safely).
Photo: Bärn Kit

Why leftovers can be risky

Cooked food does not stay germ-free for ever. Microorganisms multiply fastest between 10 and 50 °C, writes the Kantonales Laboratorium Basel-Stadt (the cantonal food control laboratory) in its leaflet on temperature control (May 2026). Cooking at 70 °C or more kills many germs. The spores of some bacteria are far tougher, though: according to the leaflet, they often survive several hours at 100 °C. Below 65 °C they can germinate, and the bacteria start to multiply again.

A well-known example is Bacillus cereus. The German Federal Institute for Risk Assessment (BfR) writes in its Opinion 008/2008: the bacteria live in soil and on many plant products, especially often in rice and cereal products, but also in spices, potato salad, sauces and desserts. If such food sits lukewarm for a long time, the bacteria can form toxins. These can cause diarrhoea or vomiting.

The Basel leaflet names pre-cooked pasta, rice, vegetables, sauces and meat as foods with a higher risk. These are exactly the things that are often left over at home.

Cool quickly, do not leave it standing

The most important rule: leftovers should pass through the range between 10 and 50 °C quickly. For food businesses, the leaflet sets a maximum of two hours and says clearly: always cool food actively and never leave it at room temperature. The Kantonales Laboratorium Bern also asks for pre-cooked food to be cooled quickly in its template for childcare centres. This is how to do it at home:

  • Decant: put leftovers, even small ones, into tight containers and get them into the fridge quickly. See-through containers help you keep track (foodwaste.ch).
  • Spread it flat: lay out larger amounts in flat layers no more than 6 cm deep. That way the inner layers cool down quickly as well (Basel-Stadt leaflet).
  • Let the steam out briefly: let hot food steam off for a moment, then put it in the fridge (Basel-Stadt leaflet). That way the other food in the fridge does not warm up (foodwaste.ch).
  • Cold enough: foodwaste.ch recommends 5 °C in the fridge. How to check it is explained in Organising your fridge.

How long leftovers keep in the fridge

Even in the fridge, leftovers do not keep for long. For food businesses, the Basel leaflet says: even when chilled correctly, pre-cooked food can be stored for only about two days. None of the authorities cited here gives a fixed limit for households. But two days are a good guide at home too. foodwaste.ch advises: eat leftovers as soon as you can or freeze them.

If you know you will not eat something within two days, it is best to freeze it straight away while it is fresh. How to do that safely is explained in Freezing and thawing. Write on the container what is inside and the day you cooked it. Then you do not have to guess.

Reheating the right way: 70 °C

The Federal Food Safety and Veterinary Office (BLV) puts it briefly: when reheating food that has already been cooked, heat it to 70 degrees again. foodwaste.ch also advises reheating leftovers quickly to at least 70 degrees rather than letting them simmer for hours at a low temperature.

  • Hot all the way through: the 70 °C also apply inside. The leaflet speaks of the core temperature and, depending on the dish, recommends a probe thermometer.
  • In the microwave: stir in between so that no cold spots remain.
  • Only what you eat: reheat only the portion you are going to eat now. The rest stays in the fridge.

An old myth says you must not reheat spinach and mushrooms. According to foodwaste.ch you can, as long as you chill them quickly after cooking and bring them to at least 70 degrees when you reheat them. The myth dates from a time without fridges.

Keeping food warm: hot or cold, not lukewarm

Sometimes not everyone eats at the same time. Then there are two safe options. The BfR recommends keeping food like rice or casseroles warm between 65 and 75 °C and eating it no later than three hours after cooking. Or you cool it quickly and reheat it before eating. The Basel leaflet also names at least 65 °C for food businesses and, depending on the product, no more than three hours of keeping food warm. The range in between is the dangerous one: a lukewarm pan left on the hob all afternoon.

For kitchens, canteens and clubs

If you cook for many people, you have larger amounts and stricter duties. The Basel leaflet lists these cooling techniques: flat layers, cooling under cold running water while mixing well and, for regularly large amounts, a blast chiller. The temperature should be measured inside the product. The Bern childcare template gives these rules as an example: hot food must be delivered at 65 °C or more, and food is only served on the day it was made.

If you want to pass food on, for example after a party, further rules apply. They are explained in Passing on food safely and in the Vereinsfest-Küche (club party kitchen) tool. With the free tool übrig you go through seven hygiene questions before passing food on and keep a record. Everything stays in your browser, no account needed. For ideas on what to cook with leftovers, see the Reste-Küche (leftovers kitchen).

This article is information, not legal advice. The Basel leaflet applies to the Canton of Basel-Stadt, and the BfR opinion comes from Germany. In the Canton of Bern, the binding authority is the Kantonales Laboratorium (food control).

Sources

Also worth reading

Freezing and thawingArticleOrganising your fridgeArticlePassing on food safelyArticleReste-Küche (leftovers kitchen)Tool

Text: Richard Červenka, Bärn Kit. Found a mistake? Write to hallo@uebrig.ch.