March 1, 2008
By Pamela Accetta Smith, associate editor
Product appeal and low-cost functionality continue to make overwrap packaging a popular option amongst meat and poultry processors.
Everything old is new again, as the saying goes. And in the overwrap packaging world, the phrase is noticeably embraced. With ongoing improvements, this conventional stand-by still meets the needs of meat and poultry processors.
Overwrap, says Curtis Cundith, manager of case-ready research and development for Cargill Meat Solutions, Wichita, Kan., is a process the company has been a leader in developing over the course of the past decade, beginning with the launch of high-oxygen packaging.
“In 2002, the company implemented the use of overwrap and low-oxygen gas in smaller trays and package sizes to meet customers’ evolving needs,” he says. “One of the greatest efficiencies for us has been the number of Cargill employees with training in overwrap. We had a steep learning curve when we initially began the low-oxygen overwrapping process. However, from the installation of equipment to production, we were up and running in a month and a half.”
Cargill, Cundith explains, was able to collaborate across plants and have its experts with existing overwrap knowledge assist in training the employees who were going to be the first to use the mother-bag, low-oxygen format. That experience, he says, helped the company gain efficiencies in training, on the line and also with product delivery.
“Low-oxygen is a more sensitive type of packaging — with our new machinery and experienced employees, we’ve been able to supply customers with overwrap packages in the mother bag, low-oxygen format, which creates more flexibility in their supply chain and delivers what their consumers want — fresh meat with excellent color and taste,” he says. The use of overwrap packaging in the low-oxygen, mother-bag format is the latest development in overwrap, Cundith explains.
“Mother bags contain multiple overwrapped trays placed in a single bag that receives the low-oxygen gas,” he says.
And the process, says Cundith, goes a little something like this: Overwrapped trays are placed in the mother bag. The bag is then vacuumed and flushed with a mixture of low-oxygen gases. These gases delay microbial growth and help ensure the product has good color. A scavenger is then placed in the mother bag and begins to absorb any excess oxygen. Because there is no oxygen, it means there is no oxidation in the package. Oxidation can create an off flavor in meat. By using a low-oxygen overwrap in a mother bag, products have good color, good taste and longer shelf life.
Some of the things frequently discussed about the overwrap process, says Cundith, are the number of different ways overwrapped product can be produced.
“The first choice in the overwrap process is whether a customer would like traditional tuck-and-fold wrapping, which is wrapped and then heat-sealed to the bottom of the tray,” he says. “The other option is bead seal wrap, where a shrinkable film is sealed on the ends and the bottom and then shrinks down to the packaging.”
Other alternatives, says Cundith, include the master-bag and chip-bag packaging processes.
“Master bags contain multiple trays in a single bag, which receives an oxygen mixture. A chip bag contains a single tray in a bag and receives the oxygen mixture,” he says. “Processors can also choose between high-oxygen or low-oxygen mixtures based on what best meets the needs of their consumers and the needs in their supply chain.”
The major advantage of overwrap is that the packaging appeals to consumers.
“Overwrap has the appearance of traditional products that were cut and wrapped in the store,” says Cundith. “Low-oxygen formats offer retailers products with longer shelf life and excellent color. Whether it’s used with overwrap or another packaging format, low-oxygen can help retailers achieve a better in-stock position because it allows for flexibility in the supply chain.”
Cundith says some of the disadvantages of overwrap include weeping — where purge may make the package wet.
“Additionally, overwrap master bags involve a secondary packaging, which can affect cost,” he adds.
Overwrap technology works within two basic systems, says Huston Keith, principal and founder of Marietta, Ga.-based Keymark Associates.“The elevator system was first, where the package is pushed up against the film, then arms push it under the tray, then it is sealed,” he says. “The in-line system, which is faster, forms a tube around the line of trays, then makes a seal between trays, where it is also cut to separate them.”
For both systems, the trays go through a heat tunnel to shrink the film around the product/tray. Overwrap packaging continues to be a popular option due to its leakproof-ability and low-cost features, says Keith.
“Nearly all processors who make use of retail tray packaging utilize overwrap technology,” he says. “Especially poultry processors. And with the growth of case-ready, many fresh-meat processors have started using [overwrap packaging] as well, including Tyson, Cargill, Smithfield, Swift and several others.
“Value-added (fresh sausages and cooked products) processors also use overwrap —Johnsonville and Bryan Corn Dogs, for example. You can find other examples at your local supermarket, which also uses [overwrap packaging] for in-store cut and packaging of meat and poultry.”
Keith says the advantages of overwrap packaging include the low cost of materials and equipment and ease-of-use (can be wrapped manually if needed using PVC film; simple-to- change sizes without special tooling; and effortless use in a small facility like a store backroom, for example). The basic variable costs for overwrapping, he says, are for tray, film and electricity to operate the equipment.“Then there is the investment in equipment and a building to put it in,” he says. “Finally, there is labor to operate the equipment.”
Another benefit to overwrap is that processor-wrapped packages appear the same as in-store packages — communicating freshness to consumers and eliminating concerns about why a processor-wrapped package is different. Overwrap allows meat to protrude above top of tray, providing greater product visibility, the use of less costly trays, and the ability to fit more packages in a fixed storage/display space (versus lid-sealed MAP trays).
Disadvantages of this type of packaging (as compared to lid-sealed trays, the usual alternative) include the fact that these packages may not truly be leakproof (except at higher cost), difficulty in achieving extended shelf life (except at much higher material and labor cost), lower throughout for a given size, and lesser resistance to handling abuse.
On the horizon
There are some advances in overwrap packaging approaching in the near future. Just as overwrap has evolved using different oxygen levels and packaging methods, the technology used will also evolve. Cargill says it will continue to collaborate with equipment suppliers to create new machinery and technology to make the process more automated and efficient.
“Right now, the low-oxygen, mother-bag overwrap process is fairly time- and labor-intensive,” says Cundith. “Specially designed machinery will help make the process more automated and efficient. We are collaborating with equipment-supply companies to share what is essential to the overwrap process so that we can spur the advancement of more automated, customized machinery.”
Cundith says he is also seeing advances in the types of materials used. Companies are working to develop more advanced oxygen scavengers that have a longer life.
“Currently, a scavenger — which absorbs oxygen in the mother bag — has a limited active working time,” he says. “Cargill is anticipating the development of new scavengers that will work faster and longer before they reach the end of their useful life.”
Another future advancement Cargill anticipates is the incorporation of package components — such as the scavenger — into the packaging trays themselves.
“Activated packaging is where tray components include scavengers or antimicrobial agents,” Cundith says. “This would eliminate extra elements in the packaging and make the process more efficient.”