How to use microwaves safely in your food business.

This article has been written by Pilla Founder, Liam Jones, click to email Liam directly, he reads every email.

Food poisoning frequently occurs when microwave ovens have been used to cook food. This is quite often due to the user not understanding the science behind how microwaves work or failing to follow the procedures specific to the use of microwaves.

At a microscopic level, microwave energy causes water molecules in food to vibrate at thousands of times per second creating heat. This heat then radiates through the food.  Unfortunately, due to the nature and texture of different types of foods, they differ in density in different parts of the food and therefore do not cook evenly through the product.

Normally, foods cooked in microwave ovens need turning, rotating and stirring in order that all parts are adequately cooked, it is also important that a certain amount of standing time is also observed to allow heat to radiate through foods to cook them to safe temperatures.

It is very important that when probing microwaved foods that the tip of the probe reaches the parts of the food that are the most unlikely to have cooked properly i.e. The densest or thickest part of the food.

Type

Commercial grade microwave ovens must be used only, they are designed for prolonged and continuous use, they are built more sturdily, they are easier to clean and break down less frequently.

Containers

Only use containers that are safe to use in a microwave oven, they must be non-porous, must not warp or melt and must be of a material where dangerous chemicals cannot leach from them into food.

Any cling film or wrappings used with containers must be food grade and able to be microwaved safely without leaching toxic chemicals into food.

Metal use

Metal containers, utensils, crockery or any other non-food item place in a microwave oven must not contain metal.

Metals reflect microwave energy and can cause damage, electrical surges and fires.

Correct use

Depending on the type of food being cooked, the food should be turned, stirred or rearranged to ensure all parts of the food are cooked properly.

Users should also observe standing time at the end to allow for heat to conduct through the food.

Always check food with a food probe to ensure correct core temperatures are reached, as visual checks such as steam and bubbling cannot be entirely relied on to indicate that the product has cooked fully throughout the product.

Special conditions

Any food with a skin or membrane can explode if not pierced before cooking. This is because steam can build up within the skin or membrane which will eventually explode as the pressure builds to a point where the skin/membrane can no longer hold the pressure.

Additionally, ready-made meals with a cellophane lid must also be pierced before cooking for the same reason.

Always pierce these types of food top avoid accidents.

Defrosting

Foods must not be defrosted unless the oven contains a defrost setting.

Only defrost foods in a microwave where the manufacturer states that this can be done safely.

Always follow manufacturer’s instructions regarding defrosting in regard to settings i.e. Temperature/timings.

Once defrosted foods must be cooked / reheated immediately.

Maintenance

Ensure that the microwave is kept in good condition and that regular maintenance checks are carried out.

Faulty and unmaintained microwaves may not cook foods safely or efficiently.

Cleaning

Microwaves must be cleaned often as part of the cleaning schedule, they should also be cleaned before and after use for certain situations such as when required for cooking foods containing allergens, they should also be cleaned immediately when spillages have occurred.

Care should be taken to clean all surfaces including the ceiling of the unit, ensure that cleaning chemicals are suitable for this task.

Microwave use

Do not use any metallic objects in the microwave. Remove any objects that cause sparks immediately.

Do not use the microwave if the oven cavity is dirty, clean and disinfect first.

Do not operate a microwave without a clean stirrer cover in place.

Clean and disinfect the microwave after every service period, removing the stirrer cover first, which should be cleaned thoroughly before being replaced for next use.

Corrective actions if things go wrong

• •Purchase new microwaves if the current ones are not commercial quality, breakdown frequently or are inefficient. Repair/replace broken or faulty equipment.
• •Use alternative equipment if the microwaves are not working correctly.
• •Purchase food grade microwaveable containers.
• •Foods that may have been cross contaminated must be discarded.
• •If staff do not follow the safety points above, then retrain them and increase supervision until competency can be shown.