Good Fruit Grower

January 15

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TIPS for STORING Honeycrisp As volumes increase, Honeycrisp will need to be stored longer. PHOTO BY GERALDINE WARNER by Geraldine Warner Don't let Honeycrisp's firmness fool you, says Jim Mattheis, USDA physiologist. irmness is one quality aspect of Honeycrisp apples that producers don't need to worry too much about, but this can lull them into a false sense of security, Dr. Jim Mattheis warned during a Honeycrisp Fruit School in Washington in December. "One of the great things about Honeycrisp, from a postharvest management perspective, is that firmness really is not what we're worried about," said Mattheis, a postharvest physiologist with the U.S. Department of Agriculture in Wenatchee. "We've seen this consistently where fruit that's picked at a relatively low firmness of around 12 pounds doesn't tend to fall apart when it's in storage. "That's certainly a strength from the marketing perspective, but it can also provide you with a false sense of security," he added. "If you're relying on a firmness estimation to tell you whether or not you have good quality, you can fool yourself because other components of quality of Honeycrisp are very important and they can go away before you see a drop in firmness." David Bedford, breeder at the University of Minnesota, where the variety originated, said Honeycrisp is one of the longest-storing apples in existence. "I know it has the capacity to store like none I have ever seen," he said. But the apple is susceptible to a whole host of postharvest disorders. These include soft scald and soggy breakdown, which are related to exposure to low temperature as the fruit comes off the tree and goes into cold storage. It's important not to cool them too rapidly, Mattheis said, so holding Honeycrisp apples at a temperature of 50°F for a week before cold storage is the key to managing such disorders. The apple is also subject to low-oxygen or carbondioxide injury. And it can develop core flush just from being stored too long. F Soft scald Susceptibility to soft scald or soggy breakdown varies significantly from orchard to orchard. Mattheis and his colleagues studied fruit from a number of orchards to try to find out if susceptibility was related to certain maturity indicators or orchard factors, but they were unable to discover why fruit from one orchard might develop the disorders while fruit from another did not. Scientists are still trying to get a better handle on how likely a particular lot of apples is to develop chilling injuries, but, in general, fruit harvested more mature seems more susceptible. So, if the grower has delayed harvest waiting for the fruit to color, even if the fruit is held at 50°F before going into cold storage, the disorders might still develop. And, delaying cooling can lead to earlier development of bitter pit and greasiness and loss of titratable acids, which affects the flavor. Both CA (controlled atmosphere) storage and treatment with MCP (1-methylcyclopropene) can slow acid loss and development of greasiness. Where carbon-dioxide injury is a problem, the antioxidant DPA (diphenylamine) can reduce but not eliminate the risk of injury in CA, Mattheis said. Maturity indicators Fruit with a higher acid level tends to taste better when it comes out of long-term storage. But Mattheis stressed that this does not mean the fruit should be 20 JANUARY 15, 2014 GOOD FRUIT GROWER

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