MEDFORD - Pear fans may soon buy their own favorite fruit peeled, sliced and ready to eat from the supermarket. The challenge is to keep the same fresh taste and texture the fruit had when first peeled and sliced up to a few weeks before.
Oregon State University researchers have identified treatments for fresh sliced pears that will inhibit pear browning and textural deterioration. They have also learned what causes pears to deteriorate, which will help in the development of a more consumer-friendly product.
"The pear is a challenge compared to, say, the apple," said David Sugar, a plant pathologist at OSU's Southern Oregon Experiment Station at Medford. "The pear has a narrow window of eating ripeness."
Sugar, graduate student Xiaoling Dong, and OSU food scientist Ron Wrolstad have been studying pear behavior to see what treatments would keep pears fresh the longest.
"First, we're trying to identify the proper moment of maturity - when a pear should be sliced," Sugar said. "Then we want to see what inhibits the browning and what inhibits textural deterioration."
The scientists have found a variety of treatments that will inhibit browning and deterioration of fruits. In apples, for example, ascorbic acid (vitamin C) works very well. However, ascorbic acid would only keep pears fresh 5-7 days. "We continue to look at a range of materials that keep pears fresh longer, and we think we've found an excellent prospect," Sugar said.
The "winner" is 4-hexylresorcinal, the same compound used to keep fresh shrimp looking pink, and an ingredient in throat lozenges. The chemical does not have FDA approval for fruit as yet, but processors have applied for that approval.
"Our research shows 4-hexylresorcinal can keep pears from browning for 30 days or more."
Another ingredient, he said, is calcium lactate.
"This compound has already received FDA approval, is safe to use and enhances the ability of sliced pears to retain their firmness and texture," Sugar said.
Even with the chemicals, keeping pears fresh will require special treatment - what Sugar calls "keeping the cool chain."
"Pears will be more work than dipping them in vitamin C," Sugar said. "We'll have to keep the pear cool from manufacturer to consumer. The slicing will be done in a cold room, packages will be stored in a cold room. The pears will be shipped in a cold truck to a refrigerated distribution center, then sent to a grocer's refrigerated shelf."
For pear fanciers, all the work will be worth it, the researcher believes.
"We grow good pears here and a lot of them," Sugar said. "We're looking for new ways to give the consumer the benefit of that quality."