Stemfree Sweet Cherry Study Makes Progress

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Researchers with the International Marketing Program for Agricultural Commodities & Trade (IMPACT) Center have made progress towards understanding the storability and consumer acceptance of stemfree, mechanically harvested sweet cherries.

“We’ve made significant progress in several areas,” said Matthew Whiting, the program leader for the stone fruit physiology program at WSU Prosser’s irrigated agricultural and extension research center.

Whiting and Ph.D. student Erick Smith have been studying critical aspects of the mechanical harvest system including the roles that the stem and harvest system play in fruit storability.

“We conducted dye uptake studies to see if the stem draws moisture from the fruit while being stored,” said Whiting.

The dye uptake tests suggest that the stem can be a significant cause of water loss during storage, especially when stems are trimmed during processing. These results suggest that stemfree fruit may last longer in storage than fruit with stems, said Whiting.

The research team also studied how the harvesting system, such as a mechanical harvester versus the fruit being harvested by hand, affects the amount of fresh fruit that is packed and shipped for sale.

“We collaborated with the Western Sweet Cherry Group in our research and were able to run our fruit through their commercial packing line, making this research commercially realistic,” said Whiting.

The fruit was harvested using Dr. Don Peterson’s (USDA-ARS) prototype mechanical harvester and by hand. When ‘Bing’ fruit was treated with Ethephon, a growth regulator which aids in the separation of the stem and fruit, the mechanically harvested fruit had fewer culls than those picked by hand – 85 percent pack out compared to 75 percent.

Whiting’s mechanical cherry harvester in action during 2006 in the Yakima Valley.

A different cultivar, ‘Skeena’, had a similar percent of marketable fruit, about 80 percent pack out for both mechanical and hand harvested fruit. These results show great promise to improve labor efficiency with mechanized harvest without having a negative impact on fruit quality, said Whiting.

In addition to the storability portion of the study, Whiting and his research team are conducting consumer acceptance panels. Through these panels consumers were asked to compare sweet cherries with and without stems.

“The 2007 trials support the 2006 findings where consumers are willing to purchase stemfree sweet cherries,” said Whiting.

Whiting and his team were able to travel to Australia to conduct these panels. Australian consumers were asked at the end of the taste test which cherry they preferred; 55 percent of consumers choose the stemfree cherry, while 45 percent favored a cherry with a stem.

The IMPACT supported portion of the study is focusing on emerging markets for stemfree sweet cherries. It also investigates what fruit qualities consumers feel are the most important and their willingness to pay for fruit with those attributes.

“We thought that consumers in Australia would feel that stemfree fruit should be cheaper because it might have been viewed as a lesser product without its stem,” said Whiting. “However, 74 percent would pay the same price as stemmed fruit, 8 percent would pay more and 4 percent would pay less.”

Whiting is encouraged by the progress the project has made in 2007 and says there have also been significant advances toward a specialized tree training system which allows them to be more suited for the mechanical harvesting system.

- Samantha Graf
IMPACT Communications Specialist

Photos courtesy of Andrea Young, Molly Bull, and Google