I love having leftovers in the fridge. They save so much time because one lot of cooking can produce enough food for more than one mealtime.

We often use leftovers for lunch the next day or freeze them for a quick-prep meal down the track. However, without safe storage of the leftovers, there is potential for bacteria or mould to grow. This could lead to food poisoning which is not conducive to harmony in the home.

Here are six guidelines for safe food storage practices. Some of them you may not be aware of.

Cool leftovers as quickly as possible 

Before putting cooked food in the refrigerator or freezer, loosely cover and cool it to room temperature. Putting hot food in the refrigerator or freezer may cause the temperature of the surrounding food to rise to an unsafe level. Also, if you cover hot food tightly, it will trap the water droplets formed from condensation and create small puddles in the food. 

If there is a large amount of leftovers, separate them into smaller single-serve portions as they will cool down more quickly.

Once the food is at room temperature, cover it with an airtight lid and refrigerate or freeze it immediately, preferably within 90 minutes and definitely within two hours after preparation¹.

Use containers that leave the least amount of air around the food. Some like to use vacuum bags or Ziplock bags, however, as I try to avoid using plastic, I use shallow glass containers with an airtight, clip-lock, silicon lid.

Use glass in preference to plastic storage containers

Glass is cleaner than plastic as it has a non-porous surface that will not absorb food, odours, and bacteria. It can also be washed at high germ-killing temperatures without warping or releasing toxic chemicals. Even BPA-free plastics are prone to releasing toxic chemicals if heated by the dishwasher or microwave.

Even freezer temperatures can cause plastics to deteriorate and leach phthalates and BPA into your food, especially during defrosting². Phthalates are hormone-disrupting chemicals used to create the flexibility of some plastics. 

Besides glass, other options are stainless steel or ceramic. Though, these do not have the benefit of being see-through. Out of sight can mean out of mind and the leftovers may get unintentionally left in the fridge for longer than the suggested three days.

Check the temperature of your refrigerator 

This is to ensure it is keeping food cold enough. The recommended temperature range is between 3 – 4 degrees Celsius (37 – 39 degrees Fahrenheit). Two hours at above 5^oC might allow food to start warming up and bacteria to grow.

The freezer should maintain a temperature of -18°C (0°F). 

If your fridge and freezer thermometers show lines instead of numbers, as mine does, give yourself peace of mind by buying a fridge thermometer online or in a kitchen store. A lot of supermarkets sell them in the kitchen utensil section.

Use refrigerated leftovers within three days

Cooked foods with a high amount of sugar or acid, such as lemon juice or vinegar, should be okay for up to a week.

To help keep track, mark your containers with the preparation date. This is easily done using a piece of painter’s masking tape which can easily be removed afterwards.

For frozen leftovers see the guide below^3,4,5. The limits are considering the safety, flavour, and texture of the cooked food.

Defrost frozen leftovers in the refrigerator

If you defrost food on the kitchen sink or bench, there is a chance that before the middle is defrosted properly, the outside will be at room temperature for too long. The less time food is at room temperature the less chance bacteria will grow.

Completely defrosting food first will also ensure that the food will reheat properly all the way through.

Don’t reheat leftovers more than once

Repeatedly warming food increases the amount of time it spends at the ideal temperature for bacterial growth. The longer the food is warm, the more bacteria are able to multiply⁶.

Therefore, if your leftovers are from a previously home-cooked or a commercially premade dinner, then it should not be refrigerated or frozen for a second reheating.

In summary, to keep leftovers safe to consume:

1. Cool leftovers as quickly as possible. 

2. Use glass in preference to plastic storage containers.

3. Check the temperature of your refrigerator. 

4. Use refrigerated leftovers within three days. 

5. Defrost frozen leftovers in the refrigerator.

6. Don’t reheat leftovers more than once.