Packed cuts of fresh pork products commonly have a three- or four-day supermarket shelf life. But Greeley, CO-based Swift & Co.'s line of refrigerated marinated pork loin chops carry a four-week shelf life.
That remarkable shelf life is attributable to a vacuum skin packaging process and materials used at the company's Louisville, KY, facility. At the 330ꯠ-sq' plant, Swift employs two Intact(TM) skin packaging machines manufactured by Trigon Engineering in New Zealand. The equipment is represented in the U.S. by Koch Equipment Group (Kansas City, MO). Trigon also supplies the 30"-wide film web. It comprises nylon/tie layer/ethylene vinyl alcohol/DuPont's (Wilmington, DE) Surlyn®/ethylene vinyl acetate sealant. During vacuum skin packaging, this film is heated. Vacuum draws the heated film tightly around two pork chops positioned about 1" apart on a white expanded polystyrene Sealfresh(TM) tray from Amoco Foam Products (Smyrna, GA). In making the tray, Amoco extrudes high-impact polystyrene onto both sides of an EPS sheet. Later, EVOH film is laminated to the top side of the sheet, says Amoco.
Swift, whose parent company is Omaha, NE-based ConAgra, introduced seven varieties of the pork loin chops about a year ago. They are sold under the Armour® brand name, with suggested retail prices ranging from $4.29 to $4.79.
Two machines
To launch the new product, Swift purchased an Intact Model RM571 skin packaging machine that was equipped with a separate MC-57 cutting unit to cut out individual trays. As product sales grew, the company acquired an automatic Model RM575 machine with a built-in cutting unit to boost production. Added last spring, the newer machine cycles three times per minute to produce 24 packs/ min. That's about double the output of the earlier machine.
"We purchased a manual Intact machine to introduce and test the new product line," recalls Michael Swanson, Swift's assistant vp of product development. "I had seen the machine, and the look of product it produced was something we wanted to help sell the pork loin chops."
The film structure's components provide multiple benefits as well. "The Surlyn film has done one heckuva job for the product," notes Swanson. "It's especially helpful within the vacuum skin packaging process because it allows the film to conform to the product and tray and give us an excellent shelf presentation," Swanson explains. "The nylon film structure has incredible puncture resistance, and the high clarity helps us showcase this new product line." Additionally, the EVOH provides considerable oxygen barrier that helps the product gain its long shelf life.
Automated process
Swanson won't reveal specific volume or sales figures for the new product line, though he does say Swift runs the two machines eight hr/day, five days/week.
On the new machine, manually filled trays of pork chops are placed into eight cavities on a carrier at the loading station. The filled carrier cycles into the vacuum skin packaging section; third is a cutting section. The carriers are conveyor mounted, so a carrier is always at each of the three stations.
A programmable logic controller coordinates this process, with the skin packaging section dictating process flow. Within this section are top and bottom vacuum chambers. Both pull a complete vacuum of 29.9" of mercury. Initially, vacuum from the top chamber draws film upwards against a hot plate to heat the film. Once warm, the top vacuum is turned off and vacuum is drawn from the bottom chamber to pull the heated film tightly to the product and tray flanges. Heat is applied to the flanges to make the seal. Vacuum is then released and the chamber opens.
At this point, the carriers index. The carrier with the product, now vacuum skin-packed, moves into the cutting section where a mechanical punching unit cuts the film so that eight individual trays remain.
As the carriers again index, operators remove packs. Each pack receives two manually applied labels. An oval on the top of the pack shows a serving suggestion and product identification. On the tray bottom is a larger label that carries heating instructions, ingredient statement, etc.
Consumers may bake, broil or pan fry the boneless chops. The spacing of the two pork chops within the pack lets consumers use them individually. Film can be removed from one chop without affecting the other in the package.
Operators pack 10 trays per corrugated shipping case. Pallet loads are shipped to customers via refrigerated trucks.
Since introducing the 12-oz chops, Swanson tells PW that Swift has added two fajita and two stir-fry entr/es. These, too, are vacuum skin-packed using the same tray/film combination on the Intact machinery. All 11 items provide consumers with a convenient home meal.
"Our company, which was known as Monfort Pork until a year ago, is making a thrust towards more consumer-friendly products," Swanson notes. "We have an aggressive research and development program whose focus is to understand consumer needs. Consumers are seeking a broader menu idea for cuts and flavors of meats, and these products are in response to those needs. With the film we use, and the vacuum skin packaging machinery performing well, we're able to meet those needs. The equipment has already paid for itself."
