Developments in Thermoformable Film

Fresh products, such as poultry, red meat and fish product, as well as chilled ready-to-eat products place special technical and technological demands on the packaging.  The products, as frequently is thought, not require to appeal to consumers at the point of sale, but rather have to protect the freshness during transport to the wholesaler or processor. Cost effectiveness, output and hygiene are therefore right at the top of the list of requirements.
But of course the food processor is wrong in his assumptions and the consumer, although requiring a perfect product, also expects an attractive and efficient presentation.

I collected some recent developments in thermoformable film with the accent on products trays. Let’s have a look at the mono-layer food tray from Faerch Plast, the Biopolymer tray from Plantic Technologies, and the Mylar Cook thermoformable films from DuPont.

Mono layer food tray
Traditionally the meat industry has used trays produced from multi-layer or laminated materials to ensure adequate sealing with film, but the plastics recycling industry has argued against the use of multi-layer and laminated materials for food packaging due to difficulties separating them for recycling.

Faerch Plast has created MAPET II, a single layer food tray. MAPET II is said to be the next generation mono packaging product designed primarily for top sealed fresh meat and poultry. It has equivalent properties to APET/PE, but is produced from just one material and offers improved sealability than its predecessor, MAPET. And, since MAPET II has better potential to be sorted and recycled, it is hoped that the plastics recycling industry will back it as the new industry standard.

Instead of adding a top layer, a small amount of special adhesive suitable for food packaging applications is applied around the rim of each tray to ensure that it can be sealed easily. The quantity of adhesive, which has been approved for direct contact with food at temperatures up to 40°C, is so low that there will be no contamination of the waste stream.

MAPET II is produced by extruding an APET mono sheet, thermoforming the tray and integrating a robot station at which the adhesive is rolled on to the sealing flange. The trays are made using post-consumer recycled materials.

Biopolymer tray for refrigerated ready meals
It is believed that, following the trend of the European market, in the US frozen food products are starting to dwindle or be eliminated from the retail mix altogether while fresh ready-to-eat products are growing. Several (multinational) food processors have already left this market segment by selling their frozen food division.

This development will show us in the near future several interesting developments in packaging. The introduction, this year, of the refrigerated prepared foods line, called Comida del Sol from Excelline Foods is one example.
For both the flautas and the burritos of Comida del Sol the thermoforming film for the trays is a Plantic eco Plastic high-barrier material from Plantic Technologies. It’s made from corn starch. Although corn crop isn’t seen as the best ingredient for non-food products, Plantic Technologies states that due to a highly efficient conversion rate, there is minimal crop space required, and the crop has no impact on food-growing land space requirements. The company’s patented polymer technology is based on the use of high-amylose corn starch, a material derived from annual harvesting of specialized non-genetically modified corn, supplied by Corn Products International. The biopolymer is comparable in cost to other conventional plastic packaging materials.

Plantic eco Plastic consists of a core layer that is extruded in a conventional manner. Laminated to this core layer are skin layers of polyethylene (largely for heat-sealing purposes) and polypropylene (for moisture barrier). Total thickness in the Excelline Foods application is 450 microns, and of that, 410 microns is the Plantic material at the core. According to Plantic, the Oxygen Transmission Rate is less than 0.05 CC/sq m/24 hr at 23°C.
Plantic eco Plastic is not biodegradable due to the presence of the non-biodegradable skin layers that surround the starch core.

The trays for the flautas and the burritos of Excelline are made on a modified-atmosphere Multivac thermoform/seal system.
The, with flautas filled, trays are back-flushed with nitrogen to drive out ambient oxygen, before a clear barrier lidding material is applied. Refrigerated shelf life is about 37 days.
The trays for the burritos, however, are packaged under a partial vacuum and then sent through High-Pressure Processing (HPP) to give it a 60-day refrigerated shelf life.

Thermo-forming Mylar Cook films
Mylar Cook films are thermo-formable films, which were especially developed for the preparation of food in the high temperature range up to 218o Celsius (425o Fahrenheit). The food product is cooked in the oven or in the microwave in its sealed pack.

Due to this process, the aromas, vitamins, minerals and inherent moisture of the product are largely retained during the cooking process. When a certain pressure is reached, the seal seam of the pack opens by itself. The food is then browned in the open pack.
The constant heat transfer during the two cooking phases ensures that consistent cooking results are achieved and reduces the cooking time by up to 30%. Mylar Cook film is an ideal food packaging solution for sous-vide applications.

The Mylar Cook concept is now supplied in a cooperation between DuPont Teijin Films and machine manufacturer Multivac. Multivac states that its Application Centres are making capacity available for processing trials and customer consultation with Mylar Cook. In addition, DuPont Teijin Films and Multivac are supporting the scale-up of Farmland Oven Perfect Fresh Pork products “Dinner’s in the Bag”.

Mylar Cook films can be used reliably on Multivac’s thermoforming packaging machines. Short forming and sealing procedures enable a high cycle output to be achieved. The wide forming and sealing temperature range of the films makes their processing simple and reliable.

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