Aug 5, 2008

Honeycrisp Storage a Growing Challenge as Supplies Increase

As more and more Honeycrisp apples are planted and growers strive to profit from the boundless consumer demand for this crunchy, juicy apple, the marketing pattern will likely change. There’ll be more Honeycrisp to sell and more left over to put into storage, making a longer marketing season.

Hopefully, by then, growers will know how to store them.

“As perhaps the highest-profit fresh apple currently in production in Michigan – and as the most-planted apple cultivar over the last three years – there is an urgent need to learn how to store this finicky apple,” said Randy Beaudry, a Michigan State University horticulture professor specializing in post-harvest physiology.

He has outlined a program of research – coordinating with researchers in Ontario, Minnesota, New York and other eastern states that seem ideally suited to growing the variety – and is seeking support for a new controlled atmosphere research facility at MSU.

Jennifer DeEll, the fresh-market quality program leader at the Ontario Ministry of Agriculture, Food and Rural Affairs in Simcoe, Ontario, is North America’s leading authority on Honeycrisp, and she calls it the “headache and heartache” variety, from production through harvest and storage.

Its list of problems includes uneven ripening, difficulty determining maturity, bitter pit, off-flavors, soggy breakdown, core browning, carbon dioxide injury in storage, storage rots, lenticel damage and stem punctures.

If picked immature, she said, they may never mature, failing to develop the varietal flavor and being “almost tasteless.” Overmature Honeycrisp develop fermentation products and off-flavors of alcohol, acetaldehyde and ethyl acetate.

Maturity isn’t related to red color.

Currently, recommendations for harvest are to watch for the ground color to change from green to yellow, use the Cornell chart and pick when the starch index is under 6, and short for soluble solids of at least 13.5 and firmness of 13.5 pounds.

A key recommendation for storing Honeycrisp is to wait – delay cooling. Let the apples sit for five days at 50˚ F.

“The cooling delay increases shrivel, ethylene, greasiness and bitter pit, but reduces many (storage) disorders,” she said, including soft scald, brown heart and low temperature breakdown.

Treatment with 1-MCP (SmartFresh) may increase internal disorders, but will reduce ethylene production and greasiness, she said. It has little effect on firmness.

For CA storage, her recommendations, which seem applicable to most production areas west of Nova Scotia, are to store at temperatures of 38˚ F to 40˚ F after a delay of five days at 50˚ F before moving them to storage. In storage, oxygen concentration can be reduced to 1.5 percent to 2 percent and carbon dioxide levels elevated to less than 1 percent only for the first one or two months, after which they can be higher.

Use of diphenylamine (DPA) to control soft scald produced minimal results in CA storage and in cold storage seemed to help at temperatures above 40˚ F, but not when colder.

The use of 1-MCP as an orchard spray (Harvista) reduced the incidence of soft scald in CA-stored Honeycrisp

Packer experience

During the CA Storage Clinic in Clarksville, Mich., in June, two packers reported on their experiences with Honeycrisp.

“There are a lot of new varieties now and we have to learn how to harvest, pack and store them all,” said Rick Zemiatis at Riveridge Produce in Sparta, Mich. “Honeycrisp is one of the tough ones.”

Given the price Honeycrisp sells for, “we need to be perfect for the price we’re getting,” he said. He’s found that rain seven to 10 days before harvest affects handling on the packing line, increasing bruising. Clipping stems, while labor intensive, reduces stem punctures. The delay before cold storage is important. Riveridge hasn’t tried CA storage, but intends to test the benefits of 4 percent calcium chloride sprays this year.

Pat Chase of Jack Brown Produce, which handles Honeycrisp produced by about 35 growers, said there’s lots of variation among growers and the apples they deliver. He’s become a proponent of stem clipping because it reduces punctures and decay. He recommends growers use plastic bins to protect the tender Honeycrisp skin and that the bins are kept full. The firm apple suffers more when apples can move about.

At Jack Brown, they run the packing line slower for Honeycrisp to reduce bruising, and find that letting the apples sit makes them better to handle than running them the same day they’re picked. They also delay putting the fruit into cold storage to reduce soft scald.

“Honeycrisps take a lot of restraint,” he said.

They treated one small lot with 1-MCP and found it reduced greasiness but wasn’t needed for firmness. They haven’t tried CA storage yet.