Food Industry.
The use of food technical gases brings numerous advantages for small investments: the repeatability, the increase in conservation times, the improvement of the organoleptic properties, the better presentability and the reduction of waste lead to significant savings in production costs.
Cryogenic freezing
Cryogenic freezing is an alternative technique to that carried out with mechanical refrigeration systems. Below we can quickly see the main characteristics with the advantages that we can obtain for the quality of the products to be frozen through cryogenic freezing using liquid nitrogen or liquid CO2 compared to traditional mechanical methods.
- Cryogenic freezing: what does it consist of? :
Cryogenic freezing is the process of lowering the temperature of food until it reaches -18 °C at the core of the product.
In particular, this heat removal process allows the passage from the liquid state to the solid state of the water contained.
The faster this phase is, the better the quality of the frozen food, this is because the speed of the process allows for the reduction of the formation of macrocrystals responsible for the rupture of cell membranes and the loss of liquids. (as happens for example by freezing products in the freezer at home).
In fact, the main application of cryogenic freezing is precisely related to the food industry, which is why we talk about food cryogenics.
Cryogenic freezing exploits the characteristics of liquid nitrogen and liquid carbon dioxide (CO2), and this great cooling power of the two gases significantly reduces freezing times compared to the traditional mechanical method, and allows for better maintenance of the nutritional properties of various foods.
Furthermore, at low temperatures, bacterial proliferation and all related enzymatic reactions are blocked; the most fragile proteins remain intact and food safety benefits significantly. - Cryogenic or mechanical freezing, differences:
The main difference between cryogenic freezing or mechanical freezing lies in the speed at which the change of state of the water occurs. Using cryogenic liquids (up to -196°C for nitrogen and -78°C for CO2) results in a faster process compared to mechanical freezing (up to – 48°C), thus obtaining a product with fewer macrocrystals and a reduced loss of liquids. - Cryogenic freezing, main advantages:
» Lower weight loss: thanks to the freezing speed, the average loss is 0.3% compared to 8-10% of traditional systems.
» Lower electricity consumption: thanks to the fact that the refrigeration necessary for the process is provided by cryogenic gases, the only electricity consumed is that of the fans for homogenizing the temperature inside the tunnels and that necessary for the conveyor belt of the food itself; therefore, energy consumption will be truly minimal.
» Lower space required: Thanks to the higher freezing speed for the characteristics previously exposed, at the same production capacity, cryogenic freezers are much more compact than mechanical ones, up to 5 times less in occupied volume.
Modified atmosphere packaging
WHAT IT IS
The packaging technology in modified or protective atmospheres (MAP) corresponds to the packaging in consumer units of food products in an atmosphere different from the natural one and made up of mixtures of gases in different proportions: mainly oxygen, nitrogen and carbon dioxide but, potentially , also argon, helium and nitrous oxide, all defined by the European directive on additives, already implemented in Italy, as packaging gas.
WHAT IT IS FOR
Basically the purpose of this technique is to prolong the preservation of the quality of food products.
To extend the life of a food, it is evidently essential to be able to block or slow down those chemical and biological mechanisms that determine its decay or deterioration. However, even in those cases where modified atmosphere packaging does not guarantee a significant extension of shelf life, the technique can allow for better presentation. For example, a portion of fresh meat may appear to be of a more appreciated colour, a dairy product may appear less greasy on the surface and cured meats may offer slices well separated from each other, in these cases the better presentation of the food may be the only objective sought .
A COMPARISON BETWEEN STORAGE IN AIR AND IN MODIFIED ATMOSPHERES FOR SOME FOODS
| PRODUCT | SHELF-LIFE IN AIR(days) | SHELF-LIFE IN THE ATMMOSPHERE (days) |
|---|---|---|
| Fresh unpasteurized pasta | < 15 | 20-30 |
| French fries | < 15 | 21 |
| Pizza | < 28 | 36 |
| Hamburger | < 14 | 28-35 |
| Wurstel | < 20 | > 30 |
HOW IT WORKS
To understand the effectiveness of modified atmospheres it is essential to consider that food always interacts with the gases that surround it.
The “product-gas atmosphere” interactions can be of a microbiological or chemical-physical nature. The first concern the possibility of multiplication of the microorganisms present in the product; the chemical-physical ones concern the stability and functionality of important food components such as proteins, membranes, lipids, pigments, enzymes, etc.
An appropriate use of gases cannot ignore the knowledge of the nature and characteristics of the product to be packaged; in particular for a correct application of the modified atmosphere packaging technique, it is essential to know in advance:
- the perishability of the food in the air: i.e. the main causes of the product deterioration phenomenon (microbiological, oxidative, enzymatic, etc.);
- the solubility of carbon dioxide in food at different temperatures and the sensory variations associated with the dissolution of the gas;
- the behaviour of the microflora in the chosen atmosphere (the risk of proliferation of anaerobic microorganisms or of an unwanted selection of the typical microflora);
- the permeability of the packaging materials to the gases used, taking into account the storage temperature and the overall surface area;
- the hermetic nature of the packaging, i.e. the absence of micro-holes and/or sealing defects;
- the effectiveness of the packaging and air replacement operation, i.e. the choice of the most suitable type of packaging machine and of the gas delivery and mixing system;
- the evaluation of the real composition of the introduced atmosphere as well as the residual oxygen after packaging.
“TYPICAL” ATMOSPHERES FOR SOME FOODS
| PRODUCT | % O2 | % N2 | % CO2 |
|---|---|---|---|
| Sandwich bread | – | 20-0 | 80-100 |
| Pizza | – | 70-60 | 30-40 |
| Fresh pasta | – | 30-0 | 70-100 |
| White fishes | 30 | 30 | 40 |
| Fatty and smoked fish | – | 40 | 60 |
| Salmon | 25 | 15 | 60 |
| Red meat | 80-65 | 0-10 | 20-25 |
| White meat | 0-65 | 50-10 | 50-25 |
| Cold cuts | – | 50-70 | 50-30 |
| Sausages | – | 70 | 30 |
| Cheeses | – | 0-80 | 100-20 |
| Cream | – | 100 | – |
| Powdered milk | – | 100 | – |
| Coffee beans and ground coffee | – | 0-100 | 100-0 |
WHAT YOU NEED
MATERIALS.
Modern packaging is increasingly characterized by the use of flexible packaging (semi-rigid plastic bags and trays, multi-layer cardboard containers, etc.) of which plastic polymers are the main constituents. Gases pass through plastic films at a speed that varies from polymer to polymer and this justifies the fact that those polymers that have low gas permeability are indicated as barrier materials. The concept of gas barrier is not univocally defined although the terms high, medium and low barrier are commonly used.
There are not many polymers that have barrier characteristics, they are rather expensive and, at times, they do not have all the characteristics (sealability, food suitability, etc.) that are needed for food packaging. For this reason, multi-layer structures are created, coupling different materials with different techniques (such as lamination or coextrusion).
GAS.
The study of the most suitable gas mixture for each specific product requirement is the fundamental starting point for a correct and useful application of MAP technology.
SICO, present for over thirty years in the technical gas market, thanks to a wide experience gained in the sector, in collaboration with the food industries, and thanks to the preparation of its technical and scientific staff, is able to provide ad hoc solutions for all cases of application.
In addition to ensuring the study of the most suitable mixture for the specific needs of the Customer, SICO also provides top-level services and plant technologies, with mixers for the on-site creation of the desired mixture, and surveillance systems for safe control of the composition and purity. The quality of the product is guaranteed unchanged throughout the entire transport route thanks to the rigorous choice of materials and plant solutions; all in compliance with current legislation on safety and hygiene.
A list of SICO gases for food use and their relative purities is shown in tables 1 and 2.
PLANT SOLUTIONS
If the supply takes place in the form of premixed gas cylinders, SICO will design and commission specific centralized distribution systems.
These systems involve the initial conveyance of the gas to a first primary decompression station. From here, at reduced pressure, the gas is transferred directly to the production department, where a secondary pressure regulation is placed upstream of the point of use.
In the case of mixtures generated on site, the in-line installation of a suitable binary or ternary mixer is necessary (depending on the desired mixture).
In this case, the regulation of the composition of the mixture and the relative flow rates of the component gases is completely automated.
Tabella Gas SICO per industria alimentare.
| GAS | GAS SICO | Function |
|---|---|---|
| Carbon dioxide (CO2) | Carbofood E 290 | Inhibition of microbial growth. Slowing of ripening in vegetables |
| Nitrogen (N2) | Nitrofood E 941 | Reduction of oxygen content. Maintaining internal pressure in the package. |
| Oxigen (O2) | Oxyfood E 948 | Maintains the red color of meat. Slows down the development of bad odors in fish and vegetables. |
| Argon (Ar) | Argofood E 938 | Same functions as Nitrogen. |
| Helium (He) | Helifood E 939 | Same functions as Nitrogen. |
| Nitrous Oxide (N2O) | Azoto protossido E 942 | Whipped cream processing |
Tabella Miscele gas SICO per industria alimentare.
| SICO Food Mixes | Composition | Tolerance |
|---|---|---|
| ALIGAS 2 | ||
| 20 | N2 80% – CO2 20% | 0.5% |
| 30 | N2 70% – CO2 30% | 0.5% |
| 50 | N2 50% – CO2 50% | 0.5% |
| ALIGAS 3 | ||
| 66-25 | O2 66% – CO2 25% – N2 9% | 0.5% |
Esempi di utilizzo dei gas nell’industria alimentare.
Beverage
Gases used for the beverage industry
The beverage industry makes extensive use of industrial gases to improve production processes and increase product quality. These gases, due to their chemical and physical properties, are essential in different stages of production and packaging. Below is a small example of gases used for various applications:
CO2 Carbon Dioxide: Gas historically used for the production of mineral waters and sparkling drinks, as well as in oenology for carbon maceration or as a cryogenic gas for cooling and maintaining the desired temperature of crushed grapes to improve the quality characteristics.
N2 Nitrogen: Inert gas, therefore non-reactive, used to avoid oxidation of various food products, thus increasing the shelf life of the same products. Nitrogen is used to replace air, for example for the blanketing of tanks containing products sensitive to oxidation. An example of application can be found in all stages of wine processing, especially white wines.
Ar Argon: as with nitrogen, this gas is used to inert, but with greater efficiency thanks to its ability to obtain a better barrier effect thanks to its high specific gravity.
O2 Oxygen: during the production of wines, in some stages of processing it may be necessary to carry out micro or macro oxygenation operations in order to improve the alcoholic fermentation of the yeasts present. In addition, in all wineries or beverages in general, there is usually a purifier for wastewater deriving from processes that are often seasonal. When these variations in pollutant load are very marked, in case of need, oxygen can be used to support or replace other traditional air oxygenation systems. To learn more, consult our SICODEP™ “brochure” dedicated to oxygen applications in this field.
