Apples - from bust to boon

MSU researchers are helping Michigan apple growers maximize and improve storage techniques to make the most of this year's record harvest.

Adam Dietrich, MSU alumnus and grower at Leo Dietrich and Sons, is calling this year's apple crop

This year’s Michigan apple crop runneth over.

Last year’s crop was decimated by late frosts, and the feeble harvest yielded a mere 2.7 million bushels for growers. This year, however, is shaping up to be a record year, projected to top 30 million bushels.

“This year is a limb-busting crop; some of our branches are so full with apples that they snap with a little help from the wind,” said Adam Dietrich, Michigan State University graduate and grower at Leo Dietrich and Sons, based in Conklin, Mich. “A single tree from 2013 is producing more than an 8-acre block of trees did in 2012.”

The overabundance of apples is welcomed, but presents its own set of challenges. One of them is maximizing storage to avoid flooding stores with apples, crashing the market and lowering growers’ profits, said Randy Beaudry, MSU AgBioResearch horticulturist.

To produce the best apples, growers must treat their fruit like babies, from bud to bushel basket. And to maintain apples’ peak flavor during storage, in many varieties, they need to be lulled to sleep. Refrigeration has long been used by growers and grocers to lengthen shelf life. Recent innovations by growers and packers, however, combine refrigeration with reduced oxygen levels. This technique has added months to the life.

“Controlled-atmosphere storage, a refrigerated room with reduced oxygen levels, suspends the ripening process in many varieties of apples,” Beaudry said. “In a sense, we are lulling them to sleep and increasing the time that they can remain in storage.”

Growers have nearly mastered storing varieties such as red delicious and McIntosh. However, some of the prized varieties, such as Honeycrisp, remain mysterious. MSU researchers are tackling the vexing problem of prolonging Honeycrisp apples’ tolerance for storage.

Current practices allow Honeycrisps to be stored for nearly four months. New methods pioneered by Beaudry are doubling that time.

“Honeycrisps are sensitive to refrigeration and low oxygen levels,” he said. “We are working on techniques to condition them prior to storage, which lowers this sensitivity and increases storage times.”

MSU has been developing these protocols over the last five years. The new approach will hopefully be adopted industry-wide this year or next, Beaudry added.


This article was originally published by MSU Today on September 30, 2013; photo courtesy of Kurt Stepnitz.

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