Agricultural Research Service plant physiologist David Obenland adds mandarin juice to a vial for analysis of aroma volatiles.
Agricultural Research Service plant physiologist David Obenland adds mandarin juice to a vial for analysis of aroma volatiles.

Spurred by the growing popularity of zipper-skinned mandarins, a group of researchers is studying how cold storage temperatures and duration may affect fruit flavor.

The work conducted by the U.S. Department of Agriculture and the University of California, Riverside, is some of the most extensive of its kind for these specialty citrus, according to a news release.

So far, researchers have worked with the peeled fruit or juice of more than 19,000 fresh mandarins harvested from at least a half dozen research and commercial groves in California.

Most mandarins typically spend at least some time in cold storage, followed by a period of warmer storage.

One experiment has shown that cold storage temperatures affect the flavor of W. Murcott Afourer oranges, known also as W. Murcott mandarins, but not the flavor of the Owari variety.

In other work, the researchers found significant changes in several flavor-associated chemicals once Murcotts were brought out of cold storage of 41 degrees Fahrenheit into 68-degree storage.

Although the four ethyl esters may contribute to a sweet fruity aroma, at high levels they may impart an off flavor. The esters also are known as aroma volatiles and play a role in fruit flavor.

The group hopes to pinpoint optimal levels of the four chemicals.

In related research, the researchers also have found that the flavor of Murcotts and nine other mandarin varieties changes after conventional waxing in the packinghouse.

That makes sense, they say, since the coating limits fruit respiration and may allow for buildup of some flavor chemicals.