Is it safe to cook baby food in the microwave?

Question: I’m weaning my baby onto solids. Is it safe to defrost, heat and cook foods for baby in the microwave?

Is it safe to heat baby food in the microwave

Using a microwave to cook, heat and defrost baby food

Although health risks are mitigated by using a microwave oven correctly, e.g. following guidelines and using microwave-safe containers, its probably best to use a microwave in moderation – for occasional cooking, defrosting or fast re-heat.

Microwave safe containers

  • Use containers safe to use in the microwave. Safe containers are made from the following materials; heat-resistant glass, ceramic glass, unglazed dinnerware and some plastics. Plastic microwave-safe containers should be marked as such.
  • Cover the baby food with  microwave-safe cling-film or a lid. Covering the food holds in the moisture produced and helps the food to heat evenly and safely.
  • Lift the lid on one of the edges or prick holes in the cling-film so steam can escape.
  • Do not use take-out containers, margarine tubs as they can cause potentially harmful chemicals to leach into the food.
  • Do not let the microwave-safe cling film come into contact with your baby’s food.
  • Remove aluminum foil and never use metal containers in the microwave.

For more information on safe plastic containers, see BPA Free Containers for Weaning.

Cooking with a microwave

  • Cook food thoroughly, to destroy any food poisoning bacteria that may be present.
  • Follow the instructions for microwave cooking in the recipe book.
  • Consult the microwave manufacturer’s instructions, if instructions are not given in the recipe book or on the packaging. Manufacturers instructions will give you timings for cooking different foods such as fish, meat and vegetables. Remember you can’t cook a boiled egg in the microwave.
  • Make sure your microwave has a turntable to rotate the food. If not, stop the microwave and rotate the food manually.


  • Familiarise yourself with the defrost function on your microwave by reading the manufacturer’s instructions.
  • Remove food from its packaging before you defrost it in the microwave and place in a microwave-safe container.
  • Stir thoroughly to remove hotspots.
  • Once defrosted heat baby food immediately (do not set aside to fully cook later on.)
  • Heat the defrosted food as follows.

Remember: An alternative to defrosting in the microwave, is to take the frozen food out the night before and leave in the fridge overnight.

Defrosting pots of weaning purées

It’s best to check your microwave manufacturers guidelines for defrosting food by weight. A rough rule of thumb for ice-cube or small pots of baby purées are:

  • Frozen food cubes take three to four hours to thaw in the refrigerator and one to two hours to thaw at room temperature.
  • Thaw frozen food cubes, microwave for 30 to 40 seconds on de-frost.
  • Heat thawed food cubes, microwave for five to15 seconds. Check it is piping hot, then leave to cool down.

Reheating food

  • Make sure reheated food is piping hot all the way through.
  • Don’t be tempted to partially warm the food, so that your baby will be able to eat it immediately – it needs to be thoroughly heated in order to destroy any bacteria that may be present.
  • Stir the food a few times during the heating process to reduce hot and warm spots occurring.
  • Set piping hot food aside and allow it to cool to a comfortable serving temperature.
  • Check the temperature of the food by tasting it before you give it to your baby.
  • Don’t reheat it more than once, throw out any uneaten food that has already been reheated.

Jars of baby food

  • If heating a jar, place it in a bowl of hot water for a minute. Do not put it in the microwave.
  • Use a clean plastic spoon (not metal), stir well and serve your baby’s portion into a clean bowl.
  • Food left over in the jar can be stored in the fridge for up to 48 hours (do not freeze).
  • If feeding direct from the jar however, the unused portion must be discarded.
  • Always use the contents before the best before date which appears on the jar.

Remember: Never heat your baby’s bottle in the microwave. Do not heat breast milk in the microwave.


USDA, Cooking Safely in the Microwave Oven, 2006

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