Meeting the needs of consumers and ensuring economic and environmental sustainability in production: these are some of the most important challenges affecting the current agri-food chain. In this context, deep-freezing has become an increasingly common practice and has an increasingly important impact on the sector: it allows companies to preserve and distribute products for an extended period of time, without compromising their quality, exploiting the power of gases to preserve food.
But what are the most effective and efficient deep-freezing techniques? There are two main solutions: mechanical freezing and cryogenic freezing.
Although both methodologies are intended to preserve food products, they produce different effects which may affect the final quality. In this article, we will explore the differences between the two options, providing an overview of the techniques, applications, and benefits of each.
Freezing food: what it means in practice
Before examining the specific differences between mechanical freezing and cryogenic freezing, it is important to understand exactly what is meant by “freezing”.
Deep-freezing is the process of preserving food which involves a sudden drop in temperature down to -18 °C at the heart of the product, to the point where the water inside is converted into a solid form composed of microcrystals.
This process preserves the organoleptic and nutritional properties of the food by slowing down or stopping the enzymatic and microbiological activity inside the food, prolonging its shelf-life.
In particular, the advantages of this technique are:
- Long-term preservation of perishable products;
- Greater availability of out-of-season products;
- Minimisation of food waste;
- Greater flexibility in production;
- Maintenance of nutritional value;
- Reduction of risks related to food safety.
For these benefits to be perfectly guaranteed, the freezing temperature must be maintained throughout the cold chain.
Freezing or freezing: what are the differences?
Another aspect to highlight is the difference between deep-freezing and freezing. Often these terms are used synonymously, but in reality, there are peculiar implications between the two concepts which should be clarified.
While freezing is a purely industrial process aimed at the development of mass production, freezing is a more gradual process, usually used in the home.
In fact, freezing takes place more slowly, with temperatures between 0 and -18°C, causing the formation of ice crystals larger than cryogenic freezing. This technique, although useful for the preservation of food, is not a definitive solution, as, in the long run, it leads to the loss of the sensory and nutritional characteristics of the food and can compromise its overall quality.
Mechanical freezing and cryogenic freezing: two techniques in comparison
It is clear, then, that agri-food companies look at freezing as a method functional to their production activity. Ma in che modo? As previously mentioned, two main options can be used to produce a frozen food line: mechanical freezing and cryogenic freezing.
The choice may depend on the production needs and the food products involved.
Mechanical freezing: the main aspects
Mechanical freezing is the most traditional technique, historically used in industry to bring down the temperature of food.
The most common system used for this purpose is the cooling cell (or mechanical freezer) which harnesses the power of cooling liquids to gradually lower the temperature of food by removing the surrounding heat, much like the equipment we all have at home.
Typically, this type of solution, which reaches a minimum temperature of about -50°C, generates relatively large ice crystals and this can cause damage to the food cells, causing a greater loss of quality and a possible alteration of taste and texture.
Basically, the challenge of excellent freezing is played on cooling times: the faster the temperature drops, the more functional the process will be in order to protect the integrity and quality of the food. Here, as we will see later, mechanical freezing is less efficient than cryogenic.
In addition, when it comes to choosing which type of plant to implement, further inefficiencies of mechanical cooling generation must also be considered:
- Expensive initial investment: the cost of machinery is on average high
- More complex management: machines must be subjected to periodic defrosting cycles
- High energy consumption: they need a continuous supply of electricity
- Occupation of a lot of space: the size of the equipment is considerable
All in all, however, the solution of mechanical freezing could be advantageous in industrial contexts where volumes are very high and production does not follow cyclical phases, either during the day or even during the year.
Cryogenic freezing: features and advantages
The technique that gives companies more flexibility is cryogenic freezing, also known as cryo-freezing.
We have dedicated a mini guide to this solution, describing its advantages and how to implement it. This is an opportunity to highlight the main features.
Cryogenic freezing is a more advanced technique than mechanical refrigeration because it involves the so-called cryogenic agents, especially theliquid nitrogen (down to -196°C) and carbon dioxide or carbon dioxide (CO₂), liquid (up to -78°C), which, when dispensed directly onto the food, create an extremely cold environment and they also manage to halve the time compared to an equal treatment by mechanical freezing.
This is certainly the main advantage: since the process takes place very quickly, small ice crystals form inside the food, minimizing damage to food cells and water and moisture losses. This helps to maintain the quality of the product perfectly, preserving its texture, taste and nutritional values, especially for delicate or high-quality foods.
It also allows companies to respond quickly to the demand for frozen products by encouraging greater flexibility in production.
Cryogenic deep-freezing plants: the contribution of SIAD
Thanks to the experience gained in decades of working alongside agri-food companies throughout the food chain, from cultivation to distribution in the GDO and beyond, the SIAD Group arises as strategic and operational ally to foster technological and process development players who look at innovation and quality as a key factor for success.
For this reason, we have developed advanced cryogenic deep-freezing systems able to meet different specific production needs:
- Cryogenic cabinets: particularly advantageous in discontinuous or batch operations;
- Freezing coils: ideal for large continuous productions;
- Cryogenic tunnels: continuous linear equipment, perfect for modular designs and to gradually increase production capacity;
- Drum freezers or rotary tunnels: mostly used for small-sized products that require individual freezing of individual pieces.
SIAD provides ad hoc solutions and specific advice to identify the most suitable cryo-freezing plants and processes for the type of production currently in operation, but not only that, the specialist technicians can offer practical support during routine, extraordinary and scheduled servicing and maintenance.
We are always available to provide all the clarifications and in-depth information of the case: contact us for a personalized consultation.
