June 25, 1998

NC State Engineers Improve Sterilization Process of Food Packaging

Research conducted by Roger Rohrbach (left) and Mohamed Bourham at NC State could change the way that drink box packaging is sterilized.

Food packaging is of little interest to most of us while we are at the market, but modern food packaging technology has increased the safety and variety of foods available. At NC State University, engineers are developing ways to make packaged foods safer. Dr. Roger Rohrbach, professor of biological and agricultural engineering, and Dr. Mohamed Bourham, professor of nuclear engineering, are working to improve the process that sterilizes drink box packaging to make it safer for consumers and less expensive for manufacturers.

Currently, drink boxes are sterilized using a hot peroxide bath. The process is very good at reducing the bacteria population on surfaces, but it leaves an oxidant residue--an unwanted byproduct of the processing.

Bourham and Rohrbach have devised a way to use low energy electron beams deactivate (sterilize) bacteria on the surface of packaging materials rapidly and at very little cost. Low energy electron beams are found in many daily applications, such as delivering pictures to television screens and computer monitors.

"Recent medical research has shown that oxidants, such as peroxide, are harmful to living tissues. That is why peroxide is so effective in sterilizing packaging," says Rohrbach. "Today, we take antioxidant vitamin complexes because we realize that oxidants are damaging. The sterilization process we are developing would reduce exposure to harmful oxidants."

The researchers are working to retrofit a brickpack processing machine with their electron beam device. Brickpacks are popular in the boxed drink industry. The machines are able to sterilize, fill and seal several hundred drink boxes per hour. During the production process, the machine bathes the packaging material with hot peroxide and then folds, fills and seals the box without exposure to sources of contamination, such as airborne particles or human hands.

The electron beam device sterilizes the packaging by passing the box material across a small window that emits the dose of electron beams delivered to the packaging. The irradiation process takes just a few seconds and does not leave any type of residue. The technique does not require irradiation of the actual juice drink.

Bourham and Rohrbach so far have used energies as low as 55 kiloelectronvolts (keV)--55,000 volts--to successfully sterilize the packaging. Their goal is to decrease the energy used in the process to about 40 keV.

"If we can deliver a sufficient dose of electron beams at a low enough energy, then our process will not only decrease the cost of processing, it will also increase the safety of the packaging by eliminating oxidant residues," says Bourham. "Our goal is to make the sterilization process as safe as possible while keeping it low cost to the manufacturer."

Technical contacts:

Dr. Roger Rohrbach, (919) 515-6763, rohrbach@ncsu.edu

Dr. Mohamed Bourham, (919) 515-7662, bourham@ncsu.edu

Media contact:

Jennifer Weston, (919) 515-3848, weston@ncsu.edu

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