Professors’ study could bring super powers to ordinary cling wrap

By University Communications
September 23, 2014
Joongmin Shin, a UW-Stout packaging professor, holds a piece of cling wrap.

Photo: Joongmin Shin, a UW-Stout packaging professor.

Most people don’t give a second thought to cling wrap, the clear, stretchy film that covers foods we buy, such as blocks of cheese, and the leftovers we store in our refrigerators.

When it comes to packaging and food, Joongmin Shin and Naveen Chikthimmah aren’t most people.

The University of Wisconsin-Stout professors are in the midst of a grant-funded study that could, in effect, stretch the properties of cling wrap as we know it.

They’re researching whether cling wrap can be treated to help prevent yeast and mold growth on food. Not only would food be safer but producers could reduce the use of preservatives in wrapped food.

Although their study is ongoing, Shin and Chikthimmah already have generated evidence to support their theory. Their super cling wrap does inhibit the growth of spoilage from yeast and mold.

“We’re seeing some good results. We’ve definitely shown it’s possible,” Shin said. “It’s new for us and very exciting.”

Their study is following a trend in the packaging industry called active packaging, in which the “package itself becomes functional,” Shin said. “Active packaging may be able to prevent mold and food-borne pathogens. We know we can improve shelf life.”

Shin, an assistant professor in packaging, and Chikthimmah, an associate professor in food science and technology, last spring were awarded a $49,000 Applied Research WiSys Technology Advancement Grant to conduct the year-long study, which got underway during the summer.

They are focusing on cantaloupe, the exterior of which is prone to developing mold.

Shin and Chikthimmah believe that individual cantaloupes covered with their treated cling wrap could greatly reduce blotch formation and spoilage of the fruit. The concept also may be extended to prevent foodborne infections, such as listeria.

In 2011, 33 people died in a listeriosis outbreak caused by eating cantaloupes. In 2013, one person died and three were hospitalized from listeria connected to cheese made in Wisconsin.

“Most contamination happens on the surface,” Shin said. “We can’t remove all the microorganisms, but we can reduce their impact.”

To be effective, antimicrobial cling wrap would have to be used on products where there’s a tight fit, such as a shrink-wrapped whole cantaloupe, a cut half-cantaloupe or a block of cheese.

With consumers advised to eat more fresh fruits and vegetables, the study takes on added importance, Chikthimmah said. Wisconsin’s $51.5 billion a year food and agriculture industry employs 150,000 people.

“We see the package as similar to a sanitizing treatment for the surface of the cantaloupe,” Chikthimmah added.

Three-step process

Turning the cling wrap from ordinary to antimicrobial is a three-step process similar to applying a coat of paint:

  • First, they purify or “sand” the plastic film by exposing it to ultraviolet light in a laboratory machine.
  • Second, they “prime” the surface with acrylic acid before applying a spacing molecule.
  • Finally, they “paint” on the preservative, while ensuring biological activity.

The first two steps are important so the preservative bonds with the wrap and doesn’t migrate to the food.

Treated cling wrap then is tested on cantaloupe.

Early tests have been conducted on small pieces of cling wrap, a laboratory-level scale. The treatment process, however, leaves the plastic film hazy and less stretchy. Shin and Chikthimmah are working on improving those outcomes.

“We want to optimize the process so it looks better and stays stretchy,” Chikthimmah said.

Shin has worked with cutting-edge packaging systems, including a study with asparagus, in the food and medical industry. Chikthimmah has worked in food safety with small Wisconsin food processors.

Learn more about UW-Stout’s packaging program at www.uwstout.edu/programs/bsp and the food science and technology program at www.uwstout.edu/programs/bsfst.

UW-Stout, Wisconsin’s Polytechnic University, has more than 9,300 students in 45 undergraduate majors and 23 graduate majors, including one doctoral degree. UW-Stout, established in 1891, prides itself on the success of its students in the workplace, with a graduate employment rate at or above 97 percent for recent graduates. The university was awarded the Malcolm Baldrige National Quality award in 2001.