Richard (Dick) Lindenmuth, president and CEO of Styrotek (, a California-based company that designs and manufactures EPS packaging for table grapes as well as other foods  and pharmaceuticals, discusses grape packaging challenges and solutions.

Why is extending grapes’ shelflife a challenge? 

Richard Lindenmuth: Unlike some other fruits, like pears and bananas, that ripen after harvest, grapes do not. They immediately begin to deteriorate — which is exacerbated by varied temperatures from the moment they are picked in the vineyard to the time they reach the grocer’s aisle, and ultimately, the consumer. We know that high temperatures and low humidity cause water loss from the grapes and stems, which ultimately increases the rate of deterioration. Getting the grapes in a cooler temperature and providing them packaging that allows the cooler temperature to be maintained preserves grape quality. This becomes very important to extending shelflife. Maintaining the cold chain with proper cooling and storage, using expanded polystyrene (EPS) grape shipping containers, shelflife can extend up to 120 days vs. less than 10 days with corrugated boxes.

What are benefits involved in extending grapes’ shelflife (for grocers, consumers, etc.)? 

Lindenmuth: Extended shelflife is real economic for grocery stores, saving them money because of less damage and waste.  Pre-harvest grape season begins May 1 and goes until December — and sometimes into January. More than 99 percent of grapes commercially grown in the U.S. come from California. The 2015-2016 grape season had a record setting crop value at $1.76 billion.  

EPS table grape shipping containers are second to corrugated boxes with a 35 percent market share. About 50 percent of the grapes are shipped in corrugated boxes with a shelflife of less than 10 days and 20 percent waste.  

For table grapes that will be used locally within 10 days, corrugated is fine. But, for farmers and grocers who want to either hold the grapes locally for a longer period or may be shipping them across country, EPS containers can extend that time up to 120 days. (When it comes to exporting grapes, they are all shipped in EPS packaging for protection and extending shelflife.)

Preserving the grape off the vine from field to the consumer’s table is important. That’s why farmers developed EPS packaging. It was a group of San Joaquin Valley grape growers who founded Styrotek 40 years ago. Today, Styrotek is still owned by California Central Valley growers who understand the critical need to preserve the shelflife of fruit. 

Can you explain how packaging and shipping grapes in expanded polystyrene helps? 

Lindenmuth: We know that grapes begin to deteriorate immediately at harvest. So, the aim of post-harvest treatment is to limit the rate of deterioration, and that can be done by maintaining the cold-chain process using EPS packaging — enabling quality grapes to make it to the grocery store aisle — so ultimately, consumers have fresh, juicy grapes when making their decision to buy or not to buy.  

EPS is cost-effective because of its versatility and durability. Produce may stay in the same container from field to cold storage to transport and final destination. The produce is protected from damage and is shielded from moisture and/or heat. And, because the containers are lightweight, fuel costs for transport are less. 

What were the results of the UC Davis study regarding EPS packaging and shelflife? 

Lindenmuth: A published UC Davis study said that packing grapes in EPS containers has many advantages. Specifically, EPS does not absorb water; is a good insulator; and does not lose strength in refrigerated storage. Moreover, they are lightweight and can be forced-air cooled as quickly as corrugated.

EPS does not absorb water. Much of the weight loss of packaged produce is due to water absorption by paper and corrugated packaging.  

EPS is a good insulator. The combination of its good thermal insulation and lack of moisture absorption maintains grape quality.  

EPS retains its strength in high-humidity cold storage; corrugated boxes lose strength as they gain moisture in storage and transportation. EPS can stack two to three pallets high for long periods of time; corrugated can only stack two boxes high for short periods. The strength loss causes the boxes to sag after about two weeks, resulting in crushed and damaged grapes. 

EPS boxes can be forced-air cooled as quickly as corrugated. The EPS boxes are packed with less interior packaging, allowing airflow through boxes, which helps with the cooling process. 

EPS boxes are lightweight at about 1.1 lbs., which reduces trucking weight; corrugated weighs more about 1.8-1.9 lbs.

Aside from the economic upside of extended shelflife for produce such as grapes, what environmental benefits might result?

Lindenmuth: There is a lot of misinformation out there, and many people are not aware that EPS material is 100 percent recyclable and can be repurposed into a wide range of products — from bike helmets and picture frames to wine shippers.  A California nonprofit uses recycled EPS foam to make sustainable surf boards. EPS leaves a smaller footprint on the planet than other comparable materials; reduces waste in the supply chain; is ozone-friendly; and uses less fuel for transport. Many of our customers have a commitment to reduce or eliminate waste completely. EPS packaging helps companies achieve environmental priorities.

Do you see consumers as more interested in environmental impact regarding not just produce, but all of their purchases? 

Lindenmuth: The EPS industry across a broad range of industries, including EPS insulation used for non-food items such as car bumpers, is growing and expected to go from $15 billion to around $22 billion over the next few years. So there will be more emphasis on going green and becoming more sustainable. Clearly, there seems to be a systemic shift in the recycling infrastructure and establishing a circular economy for EPS.  

Recycling is an important part of sustainability and is increasing, along with the growth in new collective programs in the industry. EPS is not organic, so it has to go through a process. Shipping EPS containers that are full of air to a recycling facility can be expensive, which is one of the reasons why people are not doing it. But, one of the biggest positives in the industry over the next three or four years is new technology that recycles expanded polystyrene and massively reduces its transportation costs. 

There’s a new method we are going to be part of, an experiment in Canada, where a company called Polystyvert Inc. has invented a process where they can take our recycled material through a chemical process; restore it back to its original state; then send it back to the manufacturers of chemical resins — who will then make it into resin and ship back to us to manufacture new products. [This is] a complete, full-circle recycling using a decentralized model that helps reduce transportation costs. 

If so, what changes in the food/beverage industry might be ahead?

Lindenmuth: I do see that there’s more use of the containers (Fish Boxes, etc.) to display the fruit and other products in the stores, right in the EPS box. Therefore, there are more and more requests for printing artwork and the brand name on the containers. We will begin to do this this year ... Holiday Grapes, Goblin Grapes, etc. 

Explain how EPS differs from Styrofoam. 

Lindenmuth: The EPS material is not Styrofoam and is manufactured differently, in that the EPS manufacturing process does not use CFCs, HCFCs, HFCs or formaldehyde — which are harmful to the ozone layer.  Styrofoam—a registered trademark brand of another company — has never been used to hold food.

What are some applications for this packaging beyond grapes?

Lindenmuth: Our packaging can be used for many kinds of berries, such as strawberries and blueberries. We also supply our packaging for other types of food, as well as to the pharmaceutical industry. We invested in new technology and equipment. We have the ability to manufacture products quickly with no additional permits needed and have the supply chain. And, most importantly, we have a committed workforce to do the work.

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Editor’s Note: This was first published in Packaging Strategies News, June 2018.