ON-SITE NITROGEN GENERATORS FOR FOOD PACKAGING
This article aims to give a substantial overview about packaging gases and on-site Nitrogen generators for food packaging. To reach our purpose we should briefly discuss about the application and the benefits of on-site Nitrogen generation.
MODIFIED ATMOSPHERE PACKAGING TECHNOLOGY
The Modified Atmosphere Packaging (MAP) technology basically indicates the packaging of foodstuff in a different atmosphere from the natural one to maintain its freshness and extend its shelf-life. To lengthen the life of a food, obviously, it is essential to block or slow down all those chemical and biological mechanisms that determine its deterioration.
Even in those cases where modified atmosphere packaging does not guarantee a significant shelf-life extension, the technique may allow a better presentation, e.g. a portion of fresh meat may appear with a more appreciated colour, a dairy product may show up less greased on the surface and ham may offers slices well separated from each other. In any case, the use of modified atmospheres is not a means of rehabilitation or qualitative improvement of a poor food product but, rather, as a technological support operation that only together with other interventions (such as refrigeration, hygienic control, etc.) can achieve the desired effects.
FOOD INTERACTIONS WITH THE ATMOSPHERE
To understand the effectiveness of a modified atmosphere it is essential to consider that the food always interacts with the atmosphere surrounding it. This interaction can be microbiological or chemical-physical. The first concerns the possibility of multiplication of the micro-organisms in the product. The chemical-physical one instead affects the stability and functionality of important food components such as proteins, lipids, pigments, enzymes, etc.
Hence a proper application of the modified atmosphere packaging technique should consider the nature and the characteristics of the product to be packaged, in particular:
- Perishability of the food in the air, which is the main cause of its deterioration (microbiological, oxidative, enzymatic, etc.)
- Solubility of Carbon Dioxide in the food at different temperatures and related organoleptic variations
- Microflora behaviour in the atmosphere, to avoid proliferation of anaerobic microorganisms or of an undesired selection of the typical microflora
- Permeability of packaging materials to the gas, taking in account the storage temperature and the total surface
- Tightness of the package, i.e. the absence of micro-holes and/or closure defects
- Effectiveness of the air replacement operation, i.e. choosing the most suitable type of packaging machine, gas supply and mixing system
- Accuracy of the atmosphere composition as well as of the Oxygen residual measurement after packaging.
The air we breathe is normally composed by about 21% of Oxygen and 78% of Nitrogen, while the remaining 1% of minor gases among which Carbon Dioxide is present for less than 0,05%.
Oxidation, that is the appearance of abnormal tastes and/or odours, fat rancidity, browning and other colour changes have their main cause in Oxygen reactions with food constituents.
Moreover most microbes that can contaminate foods (moulds, acidifying, turbid and fermenting bacteria) need of Oxygen to grow and reproduce. As a consequence the first aim of the modified atmospheres for food packaging, with few exceptions, is the elimination of any contact between Oxygen and food. Below table lists the so-called “packaging gases” assimilated to food additives by the European Directive 2002/82/EC. Each of them has an identification code represented by the letter “E” followed by three digits. Not all of them have an effect on food storage, e.g. Helium is used only for packaging non-tightness detectors, while Nitrous Oxide as propellant for those aerosol products as whipped cream in cans. Another EEC standard concerning the labelling of food products has introduced the term PROTECTIVE ATMOSPHERE, which must be indicated between the labels indications when packaging gases prolong the life of the product.
Modified atmospheres consists of gas mixtures in different proportions: mainly Nitrogen, Oxygen and Carbon Dioxide but, potentially, also Argon, Helium and Nitrous Oxide.
Here below some examples of FOOD-GRADE GAS MIXTURES commonly used as modified atmospheres for typical foods:
TRADITIONAL GAS SUPPLY
All technical gases companies supply food-grade gases in compressed gas cylinders or bundles of cylinders at 200 bar-g, or in cryogenic tanks. The choice of the type of supply comes from consumption and logistics of the user company, so it is a technical-economical choice. Additionally many gas suppliers have recently developed dedicated food-grade gas mixtures under tradename, which they deliver already pre-mixed to the customers. To choose the most suitable supply of Nitrogen or of food-grade gas mixtures is sometimes problematic and it can be, in case of wrong decision, very expensive. Traditional supply methods involve rental, refill and delivery, environmental levy and order processing charges, in addition to several other problematics such as supply monitoring, payments management, storage handling and maintenance, etc. If, moreover, the price of gas and supplier’s rates continually increase while the environmental impact of truck based deliveries gains significance, the cost of traditional supply becomes extremely high and difficult to budget.
NITROGAS® MAP – NITROGEN GENERATORS FOR FOOD PACKAGING
On the base of specific utilization techniques issued by manufacturers of packaging machines, Gasgen has therefore designed and conceived NITROGAS® MAP series, a range of complete Nitrogen PSA generators for food packaging applications. On-site generation is a simple and smart solution to save money, to improve efficiency and to take full control of your supplying process, generating the exact quantity of Nitrogen at the needed purity.
With NITROGAS® MAP mixers you can compose your own food-grade mixture.
By means of Pressure Swing Adsorption (PSA) technology, NITROGAS® MAP Nitrogen generators for food packaging produce Nitrogen from industrial air class 1.4.1, ISO 8573.1-2010 standard. Dry and clean air from a standard industrial compressor and an air treatment system is essentially “sieved” to remove Oxygen and other trace gases, while Nitrogen passes through to the application. By using specially selected molecular sieves (CMS), Gasgen Nitrogen generators for food packaging make possible to obtain extremely pure Nitrogen (up to 99.999%) with a very moderate air consumption.
Not-cryogenic air separation is a well-known process, but the design and control features applied on NITROGAS® MAP Nitrogen generators help to maximise gas output and reduce air consumption, achieving the highest levels of efficiency. As a result, choosing an on-site Nitrogen generator rather than relying on an external traditional supply can lead up to 90% costs reduction: the investment’s payback period is typically between 6 and 24 months.
ON-SITE GENERATION BENEFITS
Trasparent costs: no surprises or “hidden costs”, all you need is compressed air.
NITROGAS® MAP Nitrogen generators eliminate the need for transportation and storage, so they help to minimise the environmental impact of using Nitrogen and food-grade mixtures for food processes. Moreover, the systems can help achieve safer working environments as they remove the safety risks concerned with external supplies such as storage, handling and replacing heavy, high-pressure cylinders. In conclusion, considering all above points, NITROGAS® MAP Nitrogen generators for food packaging are a win to win solution.
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