A team of Michigan State University researchers with the School of Packaging, have shown that packaging improvements can enhance the safety and improve the quality of onions.
"We focused on ready-to-use onions, which have grown to become one of the five most commonly sold vegetables in the last decade," said Eva Almenar, who also is an MSU AgBioResearch scientist. "We've found a package and sanitizer combination that led to diced onions being acceptable for purchase after two weeks of storage."
Typically, preprepared onions have short shelf lives. Once packaged, they quickly turn color, go soft, lose nutrients and flavor, and become translucent. Microorganisms also thrive as onions decompose, and pathogens, such as salmonella, can cause severe problems.
Controlling the package's atmosphere and sanitizing vegetables are not new techniques. However, finding the optimum combination of existing methods has never been tested. To that end, the scientists conducted the most-extensive evaluation of techniques that has ever been conducted.
The best packages were ones that helped maintain an atmosphere of elevated carbon dioxide and reduced oxygen. When combined with a sanitizing treatment of sodium hypochlorite, which is a common bleaching agent, onions could endure two weeks in a package yet still satisfy a panel of trained consumers.
This technique won't solely benefit onions, either. It will provide insights into other packaging advances for many vegetables, she added.
Already, Almenar is conducting research on gas composition packaging and containers made from renewable resources and others from egg whites and whey protein isolate, byproducts from the egg and cheese food industry, respectively. These practical advances, many that go directly to market, are part of the reason for the School of Packaging's top ranking by U.S. News & World Report.
