How to make food last longer on the shelf

Choosing the right packaging for your food or beverage can lead to the success or failure of a brand. But, as well as a good logo and pretty colours, your packaging needs to be able to sustain its contents. And the longer shelf life it has, the better for the producer. One way to extend the life of products is to use Modified Atmosphere Packaging (MAP) technology, which was created in the 80s and has been widely used since in pre-packaged foodstuff and prepared food and is championed by industrial gas specialist, Air Liquide.

The technique consists of replacing the air in the headspace of a package with a specific gas mixture. It is used to extend product shelf life and to provide an attractive presentation. This way, the natural deterioration of the product is slowed down and the initial fresh state of perishable products may be prolonged. It is commonly said that the shelf life extension with MAP is up to four times longer compared to a product packaged in air.

MAP helps preserve the freshness, colour, flavour and nutritional attributes of food products with an all-natural solution. This is because MAP can extend a product’s shelf life by slowing down microbial, enzymatic and physical deterioration. It also eliminates the need for chemical preservatives, provides mechanical protection for fragile products, and can optimise inventory levels. Side effects of using MAP technology is that its allows users to enlarge distribution networks to new geographies, reduces the amount of returns and food waste, and can provide an attractive package presentation for retail displays.

It is advisable to be careful, because there can be pitfalls. Temperature control, hygiene, and good sanitation practices still need to be followed during the manufacturing process. For refrigerated products, it is essential that the food product is in good condition with a low initial microbial load prior to MAP, otherwise the gases will not be able to extend the shelf life of the product. It is also important to know that refrigerated products must be stored at refrigerated temperatures, regardless of how they are packaged. If the storage temperature is higher than the recommendation, then the shelf life will also be shorter.

MAP technology also addresses all retail packaged food segments – both chilled and ambient. It is dedicated to the packaging step of the food value chain. It follows the processing or preparation steps and precedes storage and transportation ones. MAP could fit to bulk (big bags, cardboard) and portion units packaging (trays, bags).

MAP is used for maintaining the organoleptic qualities of food products for a longer period of time in most food processing markets whenever there is a risk of degradation if stored under air, such as:

• Meat and poultry customers – by far the largest users worldwide for fresh cuts and minced meat or processed products.
• Ready meals (pizzas, quiches, cooked meals, sandwiches).
• Dairy (milk powder, portioned/sliced/grated cheese products).
• Bakery products (bread, pastries, cookies, fresh pasta).
• Dry products (nuts, coffee, instant mashed potatoes).
• Fresh fruits & vegetables (lettuce leaves, grated carrot, fruit salads).
• Seafood (fish fillets and whole fish, processed seafood products).

Food Safety with MAP
Food safety is a public health priority that is presenting new challenges due to the increasing trends in global food production, processing and distribution. Consumers are regarding foodborne disease outbreaks with increasing concern.

Gases used in MAP are considered as food additives in Australia and as such must follow legislation applying to food additives including purity criteria.

Food MAP gases status depends on the local regulation concerning food additives enforced in each country, but must always be compliant to local food grade specifications and manufacturing procedures. Air Liquide guarantees that its ALIGAL range of gas products that are used in MAP complies with the Australian Food Standards Code.

The ALIGAL brand follows a Food Safety Management System (FSMS) based upon the requirements from FSSC 22000 (ISO 22000 + ISO TS 22002-1). Such a system provides evidence that Air Liquide is committed to:

• HACCP- (Hazard Analysis and Critical Control Points) and HARPC-based (Hazard Analysis and Risk-Based Preventive Controls) systems for carbon dioxide.
• Monitor O-PRPs (Operational Prerequisite Program) and CCPs (Critical Control Points) and record them.
• Implement, maintain and periodically test traceability.
• Use cylinders with specific labelling and special valves to avoid contamination.
• Manage non-conformities/deviations.
• Train people and ensure that personnel applies procedures.
What Gases Are Used in MAP?

The “atmosphere” is the gas surrounding the product. It can be active or inert. This gaseous atmosphere can be made of a single gas component (N2, CO2, O2 or Ar) or a mixture of these gases. The atmosphere can change over time if the film is not impermeable.

The mixture of gases in the package depends on the type of product, the packaging materials, the storage temperature, and the objectives sought by the food manufacturer. There are multiple gases and mixtures and the choice of the suitable one is not always straightforward. As an example, cheese would require different gas mixtures whether it is grated, sliced or in blocks.

A balance must be found between the shelf life requirements, the characteristics of the food product, and the CO2 levels in the gas mixture. It is advisable to run some MAP trials with different gas mixtures and the product, in parallel with quality and microbial analyses, in order to determine the best combination.

Carbon dioxide (CO2)) limits the growth of bacteria and slows down the development of mould, however a minimum concentration of 20 per cent in the gas mixture is required. Users must keep in mind that it is soluble in water and fats, which means that, in some cases, it can lead to package collapse and should be balanced with nitrogen. CO2 also reacts with water to produce a weak acid (carbonic acid) that could cause a flavour change in some products like tomato-based or mayonnaise-based products. When it comes to fresh fruits and vegetables, too much CO2 in the gas mixture can lead to premature spoilage since higher levels of the gas can affect the cellular structure of the product.

Nitrogen (N2) is an inert gas that is used to displace oxygen inside the package headspace in order to prevent oxidative reactions. It helps limit the growth of aerobic bacteria and is also used to provide mechanical protection for fragile products or to prevent package collapse because it has low solubility in water and fats.

Argon (Ar) has similar benefits to nitrogen as it is also inert, but it is twice as soluble as nitrogen in water. It can slow down the respiration rate of fresh vegetables better than nitrogen, thereby further increasing their shelf life.

Oxygen (O2) is usually the cause of microbial spoilage and oxidation but, in some cases, its presence is required. It is ideal for maintaining the bright colour of red meat. However, it can also reduce the shelf life, so it must be used in combination with CO2. It is essential for respiration of fresh fruits and vegetables to prevent premature spoilage or for blue cheese and mouldy rind cheese products (such as brie), to preserve the mould on the surface of the product. It can be used to prevent anaerobic conditions in produce such as fish, under which pathogenic bacteria like clostridium botulinum can grow.

Compared to air-wrapped or air-sealed packaged food product, on paper the MAP solution appears sometimes slightly more costly, mainly due to higher cost of the packaging materials. There are also indirect costs – packaging line productivity is lower (due to the fact that vacuum/gas injection sequence leads to a reduction in the number of cycles/min or packages/hour). Compared to vacuum packaging, the extra-cost of the gas is negligible; an indirect cost could be due to gas injection time (one to three additional seconds per cycle) therefore reducing packaging line productivity.

However, the benefits of MAP usually exceed its costs. The extended shelf life could be multiplied up to four times, allowing a reduction in logistics costs (storage and deliveries), production costs (optimisation of production schedules and series), and decreasing product waste.

Air Liquide can provide tailored solutions for food processors of all sizes. The company has the technical expertise to recommend the right gas solution adapted to each customer, whether it be packaging technology, packaging material, production capacity, size and shape of the product, desired product’s appearance, expected shelf life and logistics constraints.

The company can also propose multiple supply modes. Pure gases and mixtures can be supplied in cylinders and cylinder packs for small to medium food-processing lines. For larger food processing plants, Air Liquide supplies pure gases in cryogenic bulk vessels of different sizes along with on-site mixing systems when mixtures are needed.

Air Liquide also supplies customer support with its ALIGAL products. Based on its knowledge of the gas interactions with food products, the company provides solutions along with after-sales services. It has a dedicated worldwide network of international and local food and beverage experts to answer any questions related to MAP technology. It is easy for companies to access to Air Liquide expertise and resources to help companies optimise their process and operational costs.

They also offer training on safe handling of industrial gases and supply services for peace of mind that include the FLOSAFE gas reticulation system, bulk telemetry, rental of gas mixing stations, as well as maintenance and repair services. Finally, there are process services that include trials, product package atmosphere analysis and audits of packaging installations.

Air Liquide also provides gas solutions to many other industries, notably in water treatment, lab analysis, metal fabrication and healthcare.