As the U.S. Northwest readies for a heat spell, a major cherry grower in the region is using what it describes as the 'industry's leading network' of on-farm hydrocoolers to keep the fruit cool after harvest. 

It said additional technology now in place also was ensuring that cherry freshness remained high on the post-packing side.

“Cherries are extremely perishable fruits, so much that for every hour they spend over 40 degrees (4°C), it equals a day of retail shelf life lost," Stemilt marketing director Roger Pepperl said.

"Stemilt’s long-time strategy has been to put shelf life back in the retailer’s pocket by managing the industry’s best cold chain process."

A release said cold chain management had been a strategic part of Stemilt’s cherry program since its founding in 1964. Stemilt’s late founder and cherry pioneer Tom Mathison is said to have been among the first growers in Washington State to harvest cherries in the early morning hours, when temperatures were at their coolest, in order to maintain fruit firmness and quality.

Nowadays Stemilt has a large network of hydrocoolers, with a combined 15 mobile or on-farm units, which work by drenching 32°F (0°C) water over bins of cherries in order to pull the field heat out of the fruit.

Stemilt said it relied heavily on mobile hydrocoolers, which can be transported to farming sites as they harvest, in order to hydrocool cherries within an hour of harvest.

The hydrocoolers are then placed under shade cloth or permanent shade structures for additional cooling capacity. Prior to and after hydrocooling, bins of cherries are covered with protective pads that have been soaked in cold water to keeping cooling of cherries constant.

“It’s critical that we reduce the temperature of cherries as soon after harvest as possible, and investing in on-farm hydrocooling has allowed us to do that,” said Pepperl.

"We get a head start on the cold chain process and deliver cherries to our packing facilities at a temperature that helps maximize fruit freshness, firmness, and flavors."

Stemilt’s packing lines are equipped with in-line hydrocoolers in order to continue the cold chain process that began in the field. After packing, boxes of cherries are palletized and sent to cold rooms to go through a final cool down process, called tunneling.

Stemilt recently invested in six portable jet coolers that are used in the tunneling process. Each jet cooler has twin, 10 horsepower Baldor motors controlled by variable frequency drive and engineered fan blades.

The company said the technology was the first-of-its kind to be used by tree fruit producers and has enhanced its ability to quickly and effectively get cherries to their ideal shipping temperature of 33 degrees (0.5°C).

“We’re constantly working to develop and tweak what we call our ‘recipe’ for cooling cherries in order to consistently deliver fresh, firm, and high-quality cherries to consumers worldwide," said Pepperl.

"The introduction of jet coolers – which are specifically engineered for forced air cooling of produce – is helping us in our goal to deliver an even fresher product by considerably bringing down the time it takes us to cool cherries prior to shipping."

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