The words frozen and deep-frozen are often used as synonyms, however they have different meanings. In this article we will explain the difference between frozen and deep-frozen, giving you some useful advice to safeguard your health and palate.
Ideally, we should all eat only fresh foods. Follow the seasonality of fruits and vegetables, eat natural products… Over time, we have developed different preservation techniques.
Food preservation
Among the most traditional preservation techniques we remember drying and brining (products in salt or immersed in a salty liquid), not to mention “preserves” such as jams, marmalades, oil and purees. Since ancient times, “preserves” were prepared at home.
We live in the era of preservatives and food additives. A supermarket product has a very long “shelf life”. Large-scale food distribution has triggered the need to develop increasingly cutting-edge conservation methods. Putting aside preservatives (chemical conservation), we open the doors to food conservation thanks to temperature . It is in this context that we can talk about freezing and deep-freezing .
Difference between frozen and deep-frozen
Frozen foods are those foods stored at a temperature equal to and lower than -18°C. A frozen food differs from a frozen food both in application times but above all in the temperature reached.
So what is the difference between freezing and deep-freezing a food?
These two methods of preservation , as mentioned, vary in the time of application and the temperature, which is higher when it comes to frozen products .
Frozen foods generally reach a temperature of around -12°C. This is a higher temperature compared to the “at least” -18°C of deep-freezing . In addition, there is a detail that should not be underestimated: the speed of cooling. Frozen foods reach lower temperatures than frozen foods and do so in shorter times.
The speed of cooling of frozen foods has a strong impact on both the preservation of the food and the organoleptic properties of the product. Since a frozen food reaches very low temperatures in a short time, micro-crystals of water are formed that do not damage the biological structure of the food.
What does water have to do with it?
You should know that every food is made up of a variable percentage of water. Frozen foods reach relatively low temperatures but do so gradually, over long periods of time. The organic cells, rich in water, tear apart due to a phenomenon known as “cold lysis”. The ice crystals that form on frozen food are larger and this affects both the flavor, the appearance, and the nutritional qualities.
Frozen foods have the advantage of having flavor and properties almost completely unaltered compared to fresh products. For this reason, freezing is an excellent preservation system.
Which is better: frozen or deep-frozen foods?
After what has been explained, it is clear that frozen foods are “better” than frozen foods. Can you freeze food at home? Yes. With progress, freezers for home use are becoming more widespread , but these, in addition to being expensive, do not reach the cooling efficiency used in the industrial agri-food sector. In addition, there is another factor.
Even if you buy a home freezer, you cannot freeze ready-made dishes as you would need a blast chiller to perform a preliminary heat treatment.
Please note: the most modern freezers can reach temperatures of -18 °C, however it is the speed that makes the difference. A food frozen at -18 °C will certainly be more “storable” (it will have a longer “duration”, being able to postpone its expiry date) but since the low temperature is reached slowly, the microcrystals will not form and there will be an impact on the chemical-physical properties of the product: this is why the taste of a frozen food is different from that of a fresh food!
The taste of frozen food , on the other hand, is almost identical to that of fresh food.
Cold chain
A limitation (but also a strength) of frozen foods is the so-called cold chain . Specific legislation regulates the frozen food sector (DL 27 January 1992, n. 110 – Implementation of Directive 89/108/EEC on frozen foods intended for human consumption) while for frozen foods there are no specific laws but only general ones on food products.
For frozen foods, it is necessary to respect a careful supply chain in terms of temperatures. The cold chain can be translated as: “ the temperature of frozen foods must be maintained at all points of the product at a value equal to or lower than – 18°C ”. Not only at all its points but also at every stage of its life: from when it leaves the production plant until it is marketed.
This means that it must be transported in special trucks used as cold storage, that the movement of the frozen material must occur in a short time and its placement in the supermarket freezers must be done quickly. These are critical issues that are not easy to respect! This is why sometimes frozen foods that should be “good on paper” have an unpleasant taste: the cold chain has not been respected!
