MAP of the future

Long Life Solutions works with the global supply chain of fresh produce, implementing modern day post harvest procedures and film technology to improve the quality of produce from harvest through to retail. Chief executive Andrew Wright talks about the history of modified atmosphere technology, its place in today’s industry and the next generation developments leading to Modified Interactive Packaging (MIP).

THE CONCEPT OF MAP

Modified atmosphere technology was originally designed for the transportation of fresh meat from Australia in the late 1800s. MAP packaging has been used since the mid 1950s and has steadily increased as a viable method of extending the shelf life of food products.

In simplistic terms MAP means an alteration to the internal atmosphere of packaged goods so that it is different to the composition of the air we breathe.

MAP creates different sets of values to extend the shelf stableness of food by inhibiting microbial spoilage and enzyme and chemical activity. To achieve this, different mathematical combinations are used to alter the amount of gases used in most MAP applications. The major gases include oxygen (O2) carbon dioxide (CO2), (N2) and Ethylene (C2H4) with moisture to be considered.

MAP FILMS

The fascination with MAP films and the methodology behind the concept grew in the early 1980s with the introduction of MAP produce carton liners. This type of technology was constructed using precise mathematical calculations based on the ethos of MAP (namely, O2, H2, CO2) and a new value of C2H4 (ethylene). It was concluded that films could be manufactured using laser-induced micro-perforated technology to create a “permeable film” that, when hermetically sealed, was conducive for fresh produce to survive for longer periods under a rigid cool chain environment. The results were outstanding.

Once it had been commercialised in the late 1980s and early 1990s packers were instructed to use cable ties to seal the neck of the bag to create an airtight seal. Internal air was expelled from the inside, creating an atmosphere that would allow the produce inside to increase the levels of CO2 gas and reduce O2 concentrations.

As with other MAP technology it is important to know the various values of the selected produce, and in some cases different varieties, so that different films can be manufactured to suit specific produce requirements. Without this knowledge the wrong films or bag could be used by mistake. It is not possible to use the same film for all produce.

If an incorrect temperature is used, produce respiration will rapidly increase, causing high levels of moisture. This creates post-plant stress as the respiration rate dramatically increases. As a result, ethylene gas levels also rise, in some cases, creating the wrong environment for the produce. High amounts of water vapour form on the inside of the bag, which cannot escape and falls onto the produce or to the bottom of the bag in a pool. If the process is not corrected the atmosphere inside is unhealthy for produce to survive and will create an anaerobic condition.

THE DEVELOPMENT OF MIP TECHNOLOGY

The ideology behind MIP evolved in Japan in the early 1980s with the discovery of a special grade of volcanic rock. Scientists found that when the rock was ground to a certain sized particle it could be incorporated into a single layer LDPE (low density polyethylene) film.

When used with fresh produce this film created the right atmosphere to achieve similar or better results than the MAP adaptation. The only down side was the film produced an offensive odour. The technology has since been greatly improved.

The differences between MAP and MIP technology are vast. Firstly MAP technology is based on a static set of values where it is assumed the oxygen transmission rate levels are stable. This is fine if there are no fluctuations, which is the case for non-live food stuffs. However fresh produce is alive and so will respond at different levels during the post-harvest phase. The rate of respiration can fluctuate causing havoc inside a bag with a rigid set of values. In this scenario the produce packed in MAP technology cannot source extra amounts of 02 for survival, so it becomes stressed. In contrast MIP technology is able to adapt as it allows the produce to determine its own rate of exchange. In other words it could be said it “mimics” a situation as if the produce was still attached to the mother plant.

The permeability of the MIP film has been developed to allow live produce to increase or decrease CO2 levels in the air space around it. The produce senses this change in atmosphere and slows its metabolism and respiration rate accordingly via its own biofeedback mechanism, developing a suitable environment and, thus, maximising shelf life.

With MIP technology there is never a single set of values for O2 or CO2 levels within the breathable bags. Instead there is a range of values, with the optimal storage temperature being 1°C.

The rate of respiration will change depending on fruit maturity: the riper the fruit the higher the rate of respiration. If the exact OTRs are to be used to calculate the permeability of a film as with MAP then it is likely a different film, or films, would be required at the packhouse. In contrast MIP technology would only need one film. The main differences between the technologies is a more user-friendly adaptation of the product.

The most important difference is that one film can be used to suit most types of fresh produce. This is a huge bonus as packing inventory is substantially reduced with no chance of mixing up films or bags or using the wrong one.

This new technology also differs in the way the product is sealed. It is not necessary to use a cable tie, which can puncture the bag. Instead an elastic band is recommended. If a two-piece carton is to be used, a simple triple fold and tuck method is just as good since the outer carton, or lid, keeps the folds in place.

This has the added benefit for exporters who need to inspect goods during the transit phase. MIP films can also be opened and closed without any undue damage to the contents as the internal atmospheres are readily re-established by the produce once the bag is re-sealed.

LINX POUNCES WITH LASER

Linx printing Technologies has introduced a laser processing system for modified atmosphere packaging (MAP).

With an associated materials processing station, the Xymark LC laser system is designed to create micro-perforations and score flexible packaging films on high-speed production lines for MAP and ‘easy-tear’ applications. Micro-perforations maximise shelf-life and storability of fresh produce by promoting gas exchange between the inside and outside of packs, preventing the build-up of carbon dioxide that can lead to rapid deterioration of the produce and cause large-scale wastage.

“Thanks to their fundamental versatility, flexible materials are playing an increasingly important role in the primary packaging of consumer goods,” said Janine Lettau, head of sales and marketing at Linx Xymark. “Manufacturers and retailers are constantly looking for innovative ways to add value and appeal to their products, making them more appealing to busy consumers and reducing wastage for both the retailer and the consumer.”

The system is designed for continual use, and capable of non-contact scoring, which eradicates tool blunting and breakage and produces stronger and cleaner holes than other perforation methods. It is suitable for perforating a wide range of flexible packaging materials, according to Linx.

AMCOR’S ARRAY OF FILMS

Amcor Flexibles offers an array of modified atmosphere films, designed to maintain freshness and extend the shelf life of salads, vegetables and fruit.

Amcor P-Plus microperforated films are used throughout the UK, Europe and Australia for a wide range of retail and food service products, such as prepared vegetables, stir-fry mixes, asparagus, broccoli, spinach, cherries and potatoes.

As an extension of the P-Plus range Amcor has introduced P-Plus Extra films. According to Amcor’s technical applications and marketing manager, Jane Bicknell, these films are designed to have a lower level of permeability suitable for products such as prepared salads and fruit, especially in a lidded format where the surface area of breathable film is limited.

LifeSpan is a flexible carton liner that maintains the harvest-fresh quality of produce such as fresh vegetables, fruit and flowers. “It extends the storage life and distribution time to keep bulk produce fresh for up to four times longer than conventional packaging methods,” says Bicknell. “Olé, a Spanish company made up of 20 agricultural professionals who specialise in supplying fresh vegetables to importers from across Europe, use LifeSpan liners to transport broccoli.

A spokesman from Olé said: “Since using LifeSpan, Olé’s customer base has grown. This is because smaller customers can now stock the produce due to its longer shelf life. The benefits of using LifeSpan are many, but one is the elimination of the need for ice. This has meant no more leaking water and consequently a safer working environment for our staff.”

AgriFresh is Amcor’s range of speciality films, using specific film for specific products. “Each film has been developed to have a specific permeability from the expert choice of its components,” says Bicknell. “The technology ensures we choose the optimal structure, with not just the correct permeability, but also the required quality consumer attributes such as clarity, openability and feel, along with machine compatibility.”

To cater for the mass explosion in convenience products, Amcor has introduced SelfVent, a range of steam-venting systems developed especially for microwaving fresh produce.

“The range includes four different pack formats, all of which can be Amcor

P-Plus treated ensuring the correct modified atmosphere is achieved, optimising shelf life,” she says. “They are time-saving to the consumer because there is no need to be washing any kitchen equipment such as electric steamers or preparing any produce.”

Bicknell says the Amcor SelfVent Pouch has a technically proven venting seal incorporated into the pack ensuring consistent and safe venting each time.

“The Stand Up Pouch offers a great visible display on the retail shelf plus an easy to handle pack format for the consumer,” she adds, “and the pack is easy to open after cooking and perfect for adding differentiation to premium lines.

The SelfVent system is also available in a bag and lidded-punnet format.

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FFP EXTENDS LIFE: FFP Packaging Solutions has introduced Esterbreathe, its latest development in packaging film for extended shelf life. FFP is an independent flexible packaging converter, with a strong position in printed flexible packaging and lidding film, thanks to the recognition of its Esterpeel brand, according to business development manager, Gary Tee.

“The Esterbreathe range is a tailored permeability solution for fresh produce,” he says. “Taking into account the product life objectives of the packer and retailer, FFP measures the requirements of the individual produce being packaged, developing a film with optimum permeability to maximise shelf-life performance without the need for gas flushing.

“The key to the success of Esterbreathe is that it does not rely on any one technique to produce the packaging materials. FFP has developed the expertise that allows the use of particular film types, laser microperforation and other techniques to achieve the result. Esterbreathe is as much about a deep understanding of product requirements as it is about packaging materials.

Esterbreathe packaging is available for VFFS, HFFS and tray-lidding, in a clear, plain or full colour format.