PACKAGING
good things are coming in better packages
By Craig Collins
W
e are now well into the era of what’s called “active packaging,” and – like many technological breakthroughs – this one started with the military. Prior to the Persian Gulf War of 1990-1991, the Army’s Natick Soldier Research, Development and Engineering Center (NSRDEC), developer of the military MRE (Meals, Ready-to-Eat), sponsored research into baking bread that would last a long time – up to 20 weeks – without becoming unpleasant to eat. It took a few years, but researchers finally formulated bread that would retain its texture and moisture content while being sealed in a pouch. But there was another problem that remained: Bread in a pouch gets moldy. One of the researchers asked to tackle the problem was Joseph Hotchkiss, Ph.D., current director of Michigan State University’s School of Packaging, who was then a professor at Cornell University, investigating ways in which food packaging could become more functional. “Normally what a package does is act as an inert separation between a product and the environment,” Hotchkiss said. “Whether you’re talking about a bag of peanuts, a can of soup, or whatever, that package is designed to, in a passive way, separate the product from its environment. Now, there’s a lot of technology in doing this. It sounds very simple, but it’s not. “The concept we developed 27 years ago was: ‘OK, that’s fine, but what’s the next generation? Why don’t we have packaging that actually does something in an active way to improve the quality of the product, to keep it longer, to do all kinds of things that might be beneficial to the product?’” For the military’s pouch bread, it was clear that simply sealing it into a pouch wasn’t going to be
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AMERICAN AGRICULTURE
enough. “We developed a technology that would reduce the oxygen content in a barrier package,” said Hotchkiss. “Mold ... will not grow without oxygen. So just before the Gulf War, we developed a system where oxygen is absorbed by material added into the wall of the package.” The military’s pouch bread – for better or worse – can now remain in a pouch for years without losing moisture or growing mold. “Oxygen scavenging” is now just one of many active-packaging technologies in use today. One of the most significant recent advances has been the addition of antimicrobial agents. As Hotchkiss explained, “People are eating much, much less sterile food. We’ve changed our diets substantially in that respect. People used to eat a lot of canned food. You can hardly give away canned food anymore.” The bagged greens and vegetables consumers find in stores today weren’t possible 20 years ago. There is an important difference between the food in those bags and canned food: Bagged greens and vegetables are alive and respirating; if they were to be sealed in an impermeable plastic barrier, they would promptly wilt and die. The trick for producers who want to get living plants to market is to find some kind of packaging that will enable them to breathe – take in oxygen and release heat, carbon dioxide, and water – while slowing the respiratory rate enough to keep them fresh for as long as possible. In the produce section, the plastic pouch stuffed with, say, broccoli crowns is an engineering marvel: It’s a “modified atmosphere” or “controlled atmosphere” package, riddled with invisible microperforations to allow for gas exchange, while the inner lining of the plastic film may contain an oxygen scavenger to keep the levels of carbon