Introduction

The microwave is an appliance that has found its way into most households due to its practicality and how much it simplifies kitchen tasks.
Microwave heating was discovered by chance in 1945 when a physicist placed his sandwich on a radar used for locating wartime objects that emitted short waves. Later, he found the sandwich had become hot.
Not all materials react the same to microwave radiation. For example, electrically neutral objects like glass, paper, ceramic, or plastic are transparent to this radiation. However, metallic surfaces reflect the waves and the energy.

The heating process occurs because materials with polar molecules, such as water, proteins, or carbohydrates, absorb the waves and, through electronic agitation, convert that energy into heat. This is when the temperature of those molecules increases.

Application of Microwave Heating

This technique is only effective for foods that contain polar molecules capable of converting electrical energy into heat. It is also useful for defrosting food and reheating dishes previously cooked for immediate consumption. It is likewise applied in the preparation of cooked dishes.

Microwave cooking usually heats food from the inside out, but it does not occur evenly, as it depends on the distribution of water in the food.

The surface of the food never reaches temperatures above 100°C, so browning reactions such as the Maillard reaction or caramelisation do not occur.
Heating is often uneven, which is why microwaves are equipped with a rotating plate to distribute the waves and heat more evenly.

It is a method that is not particularly microbiologically safe. For example, in pork, it ensures the death of *Trichinella spiralis* larvae. However, in poultry, it is less effective at destroying pathogenic bacteria such as *Staphylococcus*, *Salmonella*, or *Clostridium*.

Advantages of Microwave Cooking

In general, microwave cooking allows for faster heating and lower energy consumption. It also helps preserve better nutritional and organoleptic quality.

One common concern regarding microwave cooking is whether food retains any electromagnetic radiation. This is not the case—such effects have not been observed in treated foods.

Physical Effects of Microwave Cooking

This type of cooking is similar to cooking in a water-based medium, as temperatures never exceed 100°C. It could be compared to steaming or boiling.
Maillard and caramelisation reactions do not develop, meaning no golden crust is formed on the food—making it, let’s say, a bit blander. It is also not suitable for frying, though it can be used for slow confit-style cooking at low temperatures.
Cooking is very fast, so food doesn’t dry out too much. However, it is important to consider the water content of food before cooking. For foods with low water content, precautions should be taken—such as covering the food or cooking it for less time.
Because cooking is so fast, meat does not tenderise.

Chemical Effects

Certain parameters must be considered when cooking in the microwave to avoid disaster:

• Salty foods heat up more quickly than unsalted ones.
• Water containing dissolved salts heats up much faster than pure water.
• Meat retains the grey colour of oxymyoglobin, which is not denatured.
• For eggs, which coagulate at around 60°C, this is an ideal cooking technique.
• Vegetables can be cooked in very little water, which preserves their mineral content.
• Size matters: if food pieces are too large, they may not cook properly.

Nutritional Effects

To date, the effects on fats are not well understood. After 12 minutes of microwave cooking, only 17% of the original alpha-tocopherol in olive oil remains.

Tips for Proper Use

When reheating a cooked dish, avoid using full power, as this may dry it out so much that it could burn. Always reheat at medium power and stir the food to distribute the heat evenly.

It’s always best to let the food rest for a few seconds in the microwave after cooking to prevent splashing or bubbling.

When defrosting food, make sure thinner parts are covered so they don’t become overly dry. For example, when defrosting a chicken breast, you may notice that the thinner ends begin to cook, which negatively affects later cooking.

I recommend cooking certain foods without oil and adding it afterwards. This works well for fish or vegetables, preserving the oil’s properties.

If you use plastic wrap to cover food while cooking in the microwave, make sure it is microwave-safe.

Cooking time control is very important. If you are not used to cooking with a microwave, always start with slightly less time than the recipe suggests, then add time in 30-second intervals to ensure the food cooks without burning or drying out.

Cooking time is always adjusted based on the volume of food. It’s important to read the manufacturer’s instructions, as they usually include cooking time charts.

Always keep your microwave clean; this will help it last longer and be microbiologically safer. As a rule, always cover food when cooking it to prevent splashes and also to enhance the cooking process.

What Can I Cook in the Microwave?

You can prepare savoury recipes such as sautés, vegetable creams, sauces, fish, pasta, rice, as well as sweet recipes like custards, creams, flans, and even cakes. If a recipe takes the same or more time to cook in the microwave as in the oven or a pot, I recommend using the latter. Microwave cooking is most useful when it actually saves time—because let’s face it, many foods turn out quite bland when cooked in the microwave, so you need to be selective with what you cook.

I’ve always thought it’s a great invention that saves a lot of time in the kitchen. But ideally, you should combine different cooking techniques depending on what you’re preparing. You’ll never get a crispy roast in a microwave—but that’s what ovens are for. Use all the tools you have in the kitchen; you’ll achieve far more variety in dishes and flavours.