USF Works to Improve RPCs for Strawberries

A University of South Florida Polytechnic researcher is working towards reducing the cooling time required for fresh produce in reusable shipping containers. Reduced cooling time leads to longer shelf life, according to Jean-Pierre Emond, Ph.D., dean of the College of Technology and Innovation at USF Polytechnic, and principle investigator for the project.

The study initially focuses on strawberry packaging and will expand to include other produce items.

RPC used for oranges, from IPL website

“Getting those berries that are fresh from the field cooled fast enough and evenly is one of the most important steps in maintaining quality,” Emond said in a release.

“We’re looking to achieve uniform cooling, making sure that every berry is cooled before it is shipped, and doing that in less time, all the while using reusable containers. This is a project that will benefit the farmer, the distributer and the retailer, as well as the consumer.”

Typically, farmers pack strawberries in clear plastic containers (what consumers buy at stores) that have air vents. These “clamshell” containers are placed on disposable corrugated cardboard crates that are stacked, cooled and then shipped. Currently, these cardboard crates are designed for multiple types of clamshells, so the air vents on the pallets do not match up with the air vents on the clamshells, resulting in a longer cooling time.

“Good air circulation is vital to quick cooling,” said Emond.

“If even one berry in the middle of a pack remains warmer than the rest, it will lose quality and begin to rot, risking the entire package.”

Pre-cooling produce lowers the rate of respiration, inhibits microorganism growth, restricts enzymatic and respiratory activity, reduces water loss, and lowers ethylene production, any of which would damage the produce and result in lesser quality.

In addition, he said, cardboard crates have other limitations: they can’t take a lot of weight so they can’t be stacked very high when shipped; the cardboard will begin to weaken if exposed to any moisture, resulting in damaged fruit on multiple crates; and they are typically not reusable.

Emond’s team is designing a new reusable plastic container (RPC) that will offer optimum air circulation, reduce post-harvest delays and allow more product to transfer through the cooling facility, increase strength for stacking, and are reusable.

“RPCs are showing an almost 40 percent reduction in cooling time,” he said. “They also provide better structural support and, because they stack perfectly without damaging the fruit on the bottom, are added protection for fragile fruits. And they can be reused at least 50 times. Using RPCs for produce is clearly a ‘greener’ approach to providing the very best fruits and vegetables to consumers.”

Working with Canada-based IPL, Inc., (the source of funding for this five-year, $335,000 study) researchers at USF Polytechnic are currently designing the prototype for the new RPC. IPL manufactures plastics and is producing the RPCs being used in this study.

Researchers have also been collaborating with strawberry farmers in Plant City, Florida, most recently during the local strawberry harvest earlier this year. Following the part of the project that designs RPCs made specifically for strawberries, Emond said, the study will expand to design RPCs suited best for the physical protection and temperature management needs of other fruits and vegetables.

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