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Dr. Gene Kupferman has a dream of having every piece of fruit that leaves Washington State be edible and ready (or nearly ready) to eat.    

Pears present a challenge to his vision, because they don’t travel well when shipped ripe but must be conditioned before shipment or at the retail level to speed up the at-home ripening by a consumer.

With support of the Pear Bureau Northwest, Kupferman began research last year to identify optimal pear conditioning methods throughout the storage season. He recently gave a progress report of his work with early and mid-season fruit during the North Central Washington Pear Day in Wenatchee. Additional sensory work with late-season fruit will be conducted this year. Next fall, he will evaluate different temperatures for the treatment.

"We need to increase consumption of pears," he said to the audience of growers, pointing out that annual U.S. per capita consumption of fresh pears is around 3 pounds, equivalent to about six pears per person a year. The industry has not had an abundance of new pear varieties—the way that apple and cherry growers have—to excite retailers and consumers. "It’s not going to be new varieties that will save us," he said.

Research has shown that sales of d’Anjou pears increased 40 percent when they were sold ready to eat. "Consumers will buy more pears if they know the fruit will ripen," he said. But the current state of pear merchandising, as highlighted in a retail survey conducted by postharvest colleagues across the country, found that pears were offered at a range of ripeness, with fruit from different ripening stages often mixed together.

Kupferman differentiates conditioning from ripening by explaining that conditioning is something the packer does, while ripening is what the consumer does.

Conditioned pears are partially ripened compared to a ready-to-eat, ripe pear that has a firmness pressure of between 2 and 5 pounds.

Packers and wholesalers started pear conditioning several years ago. However, a range of conditioning programs is being followed in the industry. Some packers use ethylene in the warming process, others do not. He notes that the standard approach is one day of warming the fruit to room temperatures, one day with ethylene, and then chilling fruit back to cold storage temperatures.

"Is that the right recipe? Does that do the job?" he wondered. Kupferman, along with other postharvest researchers, is looking at variety-specific conditioning programs as well as protocol changes that may be needed as the storage season progresses.

Waiting time

A component of Kupferman’s research involves pear taste tests with consumers. In collaboration with Oregon State University’s Food Innovations Center, he garnered the opinions of 250 consumers who participated in taste tests in Portland last fall. At two different times, 125 consumers tasted pears treated under different conditioning regimes and ranked fruit quality. The pears came from the same grower lot but were treated to four different conditioning programs.

"The consumer’s ideal firmness was 2 to 3 pounds for ripe-ready fruit," Kupferman said. He added that consumers ranked juiciness and sweetness as more important than firmness. Lack of pear flavor was a common reason for rejection.

When asked how long consumers were willing to wait for a pear to ripen at home to 2 to 3 pounds firmness, 55 percent responded they were willing to wait 3 to 4 days. One-third wanted to wait only 1 to 2 days, but only 10 percent were willing to wait 5 to 7 days.

"What we’re doing right now takes 4 to 7 days to ripen fruit at home and is only appealing to about 10 percent of the people," Kupferman reported.

Conditioning preferences

The treatments for early-season d’Anjou pears included being warmed for a day and exposed to ethylene for 2, 4, or 6 days or being warmed for 7 days without ethylene. The early-season Anjous had not yet met the three- to five-week chilling period that they need to adequately ripen.

Mid-season fruit that had met the chilling requirements was conditioned (warmed) and exposed to ethylene for 1, 2, or 4 days or five days of warming but without ethylene.

Consumers in the taste test sampled the early season fruit in mid October. They ranked the pears with the 6-day ethylene treatment highest, with 74 percent ranking it as the most preferred fruit and 17 percent ranking the 4-day ethylene as best. Only 2 percent liked the 2-day ethylene exposure and 7 percent liked the 7-day warming treatment with no ethylene.

The soluble solids (sweetness) of the four treatments were similar, but the firmness was significantly different. "The 7-day air treatment measured 11 pounds for firmness," Kupferman said. "That’s a rock hard pear. And the 2-day ethylene treatment was still not very good at 6 pounds firmness."

In December, when the mid-season fruit was sampled, 50 percent of consumers ranked the pears that received 4 days of ethylene highest and 23 percent preferred pears conditioned in 5 days of air, without ethylene. Pears treated to 2- and 1-day of conditioning and ethylene were only preferred by 16 and 11 percent, respectively. "These fruit didn’t soften enough for consumers’ liking," he noted.

When the consumers were asked about "liking" the fruit (considering sweetness, flavor, and texture), in the early season they really liked the 6- and 4-day conditioning and ethylene; in the mid-season fruit, they really liked the 4-day conditioning and ethylene and 5-day air with no ethylene treatment. "But it was far less clear in terms of liking in the 2- and 1-day conditioning and ethylene. Something is happening to this fruit when it’s been in storage for awhile."

A further indication that consumers are less than thrilled with the stored fruit was their response to the question of how much more would they be willing to pay for conditioned fruit. WSU economist Dr. Karina Gallardo found that the consumers in the study would pay 69 cents more per pound for conditioned pears than for non-conditioned fruit. But the price spread shrank substantially for the mid season fruit sampled in December, as they were only willing to pay 20 cents more per pound for the conditioned fruit than for non-conditioned.