Issue link: https://read.dmtmag.com/i/37334
Problems with PEAR RIPENING MCP-treated pears store longer but ripen differently. by Geraldine Warner T USDA researcher Jim Mattheis has done extensive work with MCP. he ripening inhibitor SmartFresh (MCP) holds promise for maintaining pear quality over a longer period of time and reducing disorders such as scald, but the pear industry reports that some treated pears won’t ripen. Dr. Eugene Kupferman, retired Washington State Uni- versity postharvest specialist, said Bartlett pears, which are harvested in August in the Pacific Northwest, can nor- mally be stored until December or January. Shippers are starting to use MCP to extend the season as well as to maintain the quality of pears during shipment to distant markets, but there’s a risk, he said, that the pears might still be rock hard when they reach the consumer. “It’s like the Viagra ad,” he said. “You can’t get them to relax and ripen after you apply too high a concentration of SmartFresh.” Dr. Amit Dhingra, a researcher with Washington State University, estimates that between 5 and 10 percent of Northwest pears are being treated with MCP, based on a survey of warehouses that he recently conducted for the Fresh Pear Committee. Brazil Last season, some Bartlett pears exported to Brazil were rejected by retailers and sent back to the wholesaler because the fruit remained hard, even though it turned color, said Jeff Correa, director of export promotions with the Pear Bureau Northwest. Brazil is the Northwest pear industry’s largest offshore market for MCP-treated Bartlett pears, and there’s concern about the impact of unripenable pears on consumer demand. During the Pear Bureau’s annual meeting this summer, Dennis Kihlstadius, a ripening consultant for the Pear Bureau, reported a similar situation in Vladivostok, Rus- sia. An importer he visited last season had bought eight loads of Bartlett pears from Argentina that had been shipped in March. When Kihlstadius was there in Octo- ber, the pears still would not ripen, and the importer had been able to sell only one load because he was getting no repeat sales. Bob Koehler, a regional manager for the Pear Bureau covering the northeastern United States and Canada, said he saw Bartlett pears on the domestic market at the end of April that had been treated with MCP and looked ripe, but the pressure stayed high and they never got juicy. “They had a little bit of flavor, but they were not like we expect out of a Bartlett on a regular basis,” he said. “The retailer was happy he could carry Bartletts into Jan- uary or February, but the fruit was not something that you would want to give the consumer and pin your label on it.” In fact, for the domestic market, the Pear Bureau has been strongly encouraging shippers to supply pears that have been conditioned with ethylene so they are ripe when purchased, based on the theory that pear sales increase when consumers don’t have to wait several days for the pears to ripen. Research Dr. Jim Mattheis, postharvest physiologist with the U.S. Department of Agriculture in Wenatchee, Washing- ton, has done extensive research with MCP on both apples and pears. In the controlled conditions of labora- tory research, MCP treatment of pears has been success- ful, he said, but in commercial settings, where conditions are variable, pears have responded inconsistently to treatment. “If we could predict the responsiveness and adjust the treatment protocol accordingly, I think you could proba- bly get it right every time,” he said. “But right now, nobody knows how to do that.” The recommended rate is 100 to 300 parts per billion for pears, compared with 1 part per million for apples. Mattheis said that in lab tests a rate of 300 ppb has pro- vided a nice response in terms of maintaining pear qual- ity, and the effect wears off after several months, allowing the pears to ripen. But it’s not possible to know exactly how many months the effect will last, he said, “and that’s fundamentally the problem.” 12 AUGUST 2011 GOOD FRUIT GROWER (Continued on page 14) www.goodfruit.com