EPS Packaging Achieves Grape Expectations

Expanded polystyrene packaging significantly extends the shelf life of grapes by offering moisture resistance, thermal insulation, and shock absorbency.

Expanded polystyrene packaging can extend the shelf life of grapes to 120 days from 10 days in traditional corrugated packaging.
Expanded polystyrene packaging can extend the shelf life of grapes to 120 days from 10 days in traditional corrugated packaging.
Photo courtesy of Styrotek, Inc.

Packaging and transporting table grapes can be tricky. The problem is that these delicate pieces of fruit start to deteriorate once they are picked. So packaging is crucial to maintain their freshness and prevent spoilage from the field to the produce aisle. Enter expanded polystyrene (EPS). Compared to traditional corrugated cardboard, EPS foam containers significantly extend the shelf life of grapes and protect them from damage during handling, storage, and shipping—thereby, maximizing revenue and reducing food waste—according to Styrotek, Inc., a Delano, Calif., supplier of EPS.

EPS packaging is made from polystyrene resin beads. Styrotek steams the beads, which expands them to 40-50 times their original size. It then connects and molds the expanded beads to the desired container shape. A recent study from the University of California at Davis has confirmed what Styrotek and its end users have long known: This foam packaging increases the shelf life of grapes to 120 days versus 10 days in traditional corrugated cardboard boxes. “Grape profitability can increase if the grapes are shipped in this type of foam packaging because it increases shelf life to 120 days, resulting in less damage and waste,” says Richard Lindenmuth, president and CEO of Styrotek.

About 50 percent of table grapes in the U.S. are packaged and shipped in corrugated boxes, an economical option when shipping grapes short distances. However, corrugated packaging begins to lose its durability and strength when grapes have to be transported across long distances. For example, corrugated cardboards absorbs the moisture from grapes, creating a breeding ground for bacteria. In addition, the damp boxes begin to sag after two weeks and may collapse when they are stacked on top of each other, especially in cold storage.

Expanded benefits

Unlike corrugated packaging, EPS containers can better withstand the transportation and cold storage process of grapes, Lindenmuth says. One reason why EPS substantially improves the shelf life of grapes is because the packaging doesn’t absorb humidity and encourage bacterial growth. It allows the grapes to retain their natural moisture while being stored in cold temperatures. “[EPS] does not absorb juices or act like a sponge when they have juicy grapes in the box,” Lindemuth says.

EPS boxes are also lightweight yet durable. Workers can easily load and unload the boxes and stack them two or three pallets high for long periods of times in cold storage without fear of them collapsing. Corrugated boxes with grapes can only be stacked about two boxes high for short periods. In addition, EPS provides high shock absorbency that cushions the grapes from impact in transit, helping to prevent damage to the product by 20% compared to corrugated packaging. These benefits allow processors to protect their workers from injury while maximizing storage, transit, and fuel costs.

Styrotek’s EPS packaging also has eco-friendly benefits. Because it is made of 98% air and 2% recyclable plastic, the packaging is 100% recyclable. Lindenmuth says it can be recycled into items such as bicycle helmets and surf boards. The packaging is also free from ozone-depleting chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, and formaldehyde. In addition, the manufacturing process is energy efficient with the use of steam as the primary component in producing the packaging. And Styrotek recently upgraded its equipment to lower energy use, including installing new chillers and clarifiers to reduce water usage and collect and reuse water during the process.

Now that Styrotek has improved its manufacturing process, the company wants to expand its business beyond the grape industry. It has already begun supplying EPS packaging to the pharmaceutical industry and plans to create EPS boxes specifically for berries, including blueberries and strawberries. “We’re redesigning thinner, stronger, better boxes that ultimately will be greener, but it will also cost less to the end user,” Lindenmuth says.

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