What is the ideal freezing temperature for each food?

In recent years we have all become much more aware of the importance save energy at home. Avoid turning on devices that we are not using, turning off the lights during the day if we can open the windows, filling washing machines well and many other tricks are some of the most common. But it might also be fun to play with freezer temperature or refrigerator.

There are some studies that show that, in general, these devices are adjusted too low. This means you don’t need as much cold. But is it? The answer is complicated.

It should be borne in mind that not all microorganisms and parasites They need the same temperature in the freezer. Some resist the cold better than others. It is important to talk about parasites because often we only think about microorganisms, but we should not forget about other pathogens such as Anisakis. This is not a microorganism, but nematode. A worm, to put it simply. They can also cause food poisoning and are sometimes more difficult to kill in the cold. Let’s see what this ideal freezer temperature is.

Evolution of Freezer Temperature

As a rule, freezers by default have temperature -18 ºC. This is equivalent to 0°F and for good reason. Some reports indicate that it was decided to set this temperature mainly because in countries like USAwhere Fahrenheit is used more often than Celsius.

This is obviously a good temperature, below which none of the pathogens that typically cause infections survive. food poisoning. Everything worked out, so this figure was accepted as a reference and continues to be used.

Currently, precisely because of the need to save energy, some scientists indicate the need to increase the power of these devices by several degrees. They believe that all common pathogens die at -12 ºC. Therefore, the freezer temperature can be increased. up to -15 ºCwhich will leave a small reserve in case the device does not work properly or the exciter needs a little more cold.

Will such an increase in temperature be safe?

Roughly speaking, this would be a safe increase in temperature. Most microorganisms will be more than inactivated at -15ºC. But it’s not for nothing that it is often recommended to keep the freezing temperature of fish especially low. This is due to the fact that this food, in addition to bacteria, may contain Anisakis larvae and other similar parasites.

There are several studies aimed at analyzing the ideal temperature for eliminating Anisakis. This is very important, especially if you are going to eat the fish raw. It is known that this parasite is capable of synthesizing trehalose, a substance that acts as cryoprotector. Therefore, it can be quite resistant to cold.

There are studies that show that freezer temperature kills Anisakis. Much depends on the format of the fish.. For example, in 2019, a group of Polish scientists discovered that Anisakis larvae in cod fillets susceptible to temperatures of -15 ºCbut this temperature is not low enough when the parasite is found inside a whole herring.

In this case, some even survived. -20 ºC in 24 hours. Therefore, if we are going to freeze fish, then -18 ºC is not such a bad idea. In fact, to be on the safe side, the pieces should be frozen for at least 48 hours, and if they can be cut, even better.

Ideally the fish should be tested for the absence of Anisakis. Only this week Organization of Consumers (OCU) in Spain they warned about a shipment of fish from Morocco with this parasite; but, fortunately, it was discovered before the sale. This shows that quality control is working. But even in this case, just in case, we must be consistent at home. It’s better to leave the freezer as is.