Non-Thermal Foods: The New Adventure
By Aaron Brody
Non-thermal foods are a hot topic today. A major focus of research and development teams worldwide, non-thermal processes and the packaging associated with these technologies are just now emerging from the laboratories and onto the store shelves.
“Non-thermal” is an umbrella term describing preservation processes that do not use significant temperature increases to destroy microorganisms that either cause human illness or food spoilage. Unlike thermal processing, which can deteriorate the flavor, color and texture of products, non-thermal methods do not alter the quality of foods.
Radiation is one such non-thermal process. Food is irradiated by moving it through a field of ionizing energy consisting of electron beams, x-rays or gamma rays. Many foods can be irradiated effectively, including grains, eggs, spices, and fruits and vegetables, but irradiation has greatest application for raw foods of animal origin like ground beef.
There are complications, though. Especially at-risk is the “high-oxygen” packaging of case-ready red meat, which can generate ozone when exposed to gamma or electron beam radiation. Ozone converts fresh meat pigment to an unsightly brown. Adding to the problem is the fact that regulatory authorities have not approved new packaging materials for use in food irradiation for many years.
Mitec’s IntelliBeam technology (www.mitecinc.com) might be a viable option to overcome many of the technical and regulatory challenges inherent in the process. By avoiding the direct application of radiation to the packaging, Mitec can move irradiated beef through channels with acceptable, regulated packaging. Under the brand name Corner Store, such irradiated beef is distributed chilled to convenience stores such as Kroger Kwik Shops, Handimart and in drug stores such as Walgreen’s and Osco.
Another emerging non-thermal method is pulse-field pasteurization. In this process, fluid food products are subjected to a rapidly cycling electrical impulse that partially destroys microbiological membranes and, consequently, heightens food safety and shelf life. Sterile product is then transferred aseptically or by clean fill into barrier primary packaging.
Ultra high-pressure processing
Ultra high-pressure processing (UHF) is yet another non-thermal food process. The method exposes packaged foods to extremely high pressures of more than 6,000 atmospheres, a condition that disrupts many spoilage microorganisms with little increase in temperature and without changing the product.
Unfortunately, today’s commercial packaging materials are not always resistant to the process; pressure-induced blistering and delamination of multilayer plastic structures can result. On the other hand, migration or permeation and heat-seal strength do not appear to be adversely affected. The challenge to packaging is limiting its interference to the commercial progression of the technology.
In Texas, Fresherized Foods (formerly Avomex) uses the technology for its AvoClassic guacamole (the number one guacamole in the country), and also for smoothies, fruit juices and now some chilled entrees and meats. Its Menu Fresh subsidiary offers six irradiated products including precooked fajita meats and chicken steak.
These recent successes suggest that, despite the concerns about packaging and process cycle times, the technology appears to have sufficient merit to warrant optimism.
Non-thermal processes and their affiliated packaging applications are emerging from development and edging into consumer markets, offering the potential to deliver safer, higher-quality foods closer to that ever-elusive goal of “nearly fresh”. BP
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 email@example.com