Retortable Carton: A New ‘Face’

IN THE CANNED FOOD AISLE
By Aaron L. Brody, PH.D.
Flexible pouches containing tuna, salmon, ground meat and chicken have generated excitement in the canned food aisle in U.S. supermarkets. Paperboard composite cartons are poised to make a splash in this product category, too.
Hormel Foods is rolling out two brands of chili in a retortable carton from Tetra Pak. Hormel calls the 14.3-ounce carton a “Smart Pak” that’s easy to open and pour.
To open, consumers lift the marked tabs on the sides of the carton. This exposes graphic icons showing how to open the package.
The user then squeezes the carton near the top to form a pouring area on each side of the carton, and tears off the top of the package along a perforated line.  
Other benefits of the rectangular carton include a large face panel for added shelf presence, space savings on retail and pantry shelves and weight savings compared with metal cans and glass jars.
Hormel’s research showed consumers prefer the carton. In markets where Hormel has switched from the metal can to the paperboard carton, chili sales have reportedly risen about 33 percent.
Tetra Pak refers to the package as the Tetra Recart carton, which has enjoyed success in Europe. Uses include pet food and vegetables.
Renowned for its world-wide research, development and leadership in aseptic and extended-shelf-life packaging, Tetra Pak embarked on a daring mission several years ago to package low-acid wet foods in paperboard composites.
The risk increased as Tetra Pak departed from its traditional, scored rollstock of paperboard/aluminum foil laminations in favor of preformed, knocked-down “blanks.”
To accommodate the higher temperatures of retort cooking, Tetra Pak chose a more heat-resistant polypropylene as one interior structural element. This plastic is also more resistant to flavor “scalping” or removing desirable aromas from the food product.
The carton’s duplex structure resists moisture. Its flat base is more stable on the shelf than pouches. Tetra Pak prints the carton in four process colors with a glossy coating.
Laser scoring near the carton’s top adds a perforation for easy opening. Unfortunately, the carton’s aluminum foil barrier core prevents the package from direct microwave reheating.
System engineering
Tetra Pak markets the retortable carton as a total system, embracing machinery, process technology, package materials and multi-packing.
Here’s how the system operates: Cartridges of laminated blanks run at speeds of up to 400 packages per minute. Each carton feeds into an individual carrier to be erected, induction heat-sealed, inverted and filled on a rotary piston filler.
Steam injection into the headspace of the package during filling reduces the oxygen content to permit an 18-month, ambient-temperature shelf life.
The filled cartons then enter a static retort machine, which uses pressurized steam and hot-water spray followed by cold-water spray cooling under pressure within the retort. Upon emerging from the retort cycle, the cartons are cooled and assembled into 12-packs using shrink-film bundling.
In addition to accepting the thermal process for static retorting, regulatory agencies have given the green light to rotary retorting and to a lower-speed, 100-carton-per-minute version to be commercial soon in the United States.
For more information on the Tetra Recart carton, contact Stephen Hellenschmidt at 940.367.3000 or visit www.tetrapak.com
The author, Aaron L. Brody, Ph.D., is President/CEO of Packaging/Brody Inc., a consultancy in food, packaging technology and marketing. Contact Dr. Brody at 770.613.0991 or aaronbrody@aol.com