The miracles of science™

Select Industry


DuPont™ Surlyn®

New "Combitherm Cook-in" film improves consumer appeal of quality meats

Ham or turkey breast products that can be cooked and displayed in the same package

Case Study Image

Application Description

Through a new packaging technology developed by Wolff Walsrode AG, a wholly owned company of Bayer A.G., and DuPont Packaging, a new thermoformable packaging film using DuPont Surlyn® resin is available for ham or turkey breast products that can be cooked and displayed in the same package. The new "Combitherm Cook-in" film is an extremely transparent multilayer thermoforming film with a combination of outstanding ultraviolet (UV) light absorption properties and improved oxygen barrier.
The inner layer of DuPont Surlyn® possesses properties that make packaged meat more visually appealing to the consumer. Through a crystallinity modification of nylon 6, engineers at Wolff Walsrode AG and DuPont discovered that the material provides a UV light barrier that sufficiently prevents the discoloration of food products better than any other thermoformable polymer offerings, including EVOH and PVDC coatings.
"Food products tend to discolor at UV light wave length 220 to 280 nm generated by neon light tubes used in supermarkets," said Dr. Heinrich Henze-Wethkamp, manager of application and development for Wolff Walsrode/Bayer Corporation of Burr Ridge, IL. "The new 'Combitherm Cook-in' film reduces the light transmission from 70% for standard nylon to 2%. By using the right combination of polymers for this multilayer structure, we avoid crystallinity formation and retain the functionality of the UV light barrier during the cooking process."
This innovative packaging concept also offers superior durability, visual appeal and environmental advantages over traditional packaging applications, at a retail price that fits into the current market price structure for cook-in ham or turkey breast. As a result, with "Combitherm Cook-in," the consumer will get a better quality product with extended shelf life.
The "Combitherm Cook-in" process begins when raw product is placed into cavities on a thermoforming machine, sealed and then cooked directly in the packaging mold. During the cooking process, the film shrinks and clings tightly to the meat, which prevents build-up of jelly around the edges of the ham or turkey breast. Because the meat is cooked directly in its final package, there is no product weight loss during the cooking process. The final product has a high-quality, appetizing look at the point of purchase.
"Combitherm Cook-in" uses an outer layer of polyamide (PA), plus an inner layer of DuPont Surlyn® to give the film structure strong, tight seals -- through processing, transportation and storage -- for long product shelf life. The new composite film binds to the ham or turkey breast preventing meat juice leakage and is more cost-effective than comparable materials.
Production of this innovative film is environmentally friendly and produces no scrap materials. All edge trimming can be re-incorporated into the film production through coextrusion technology. "Combitherm Cook-in" is a 20% thinner film than conventional cook-in products, requires no secondary packaging and is lighter and easier to dispose of than traditional can and liner packaging.

Because DuPont cannot anticipate or control the many different conditions under which this information and/or product may be used, it does not guarantee the applicability or the accuracy of this information or the suitability of its products in any given situation. Users of DuPont products should make their own tests to determine the suitability of each such product for their particular purposes. The data listed herein falls within the normal range of product properties but they should not be used to establish specification limits or used alone as the basis of design.

Disclosure of this information is not a license to operate or a recommendation to infringe a patent of DuPont or others.