Rapid cooling after harvest to temperatures below 39ºF (preferably 32ºF) is important to retard ripening and decay. At 32ºF and 90% - 95% relative humidity, typical storage periods for plums and IS plums* are 3-6 weeks. Shelf life varies among cultivars and is strongly affected by temperature management. Once plums and IS plums are dried, they can be stored for months.
- Plums are usually of medium size (1-3 inches in diameter) with a smooth peel that adheres to the flesh and have a single large seed.
- European plums are oval shaped while Japanese types are round to conical. Plums come in a wide variety of colors and sizes (some have yellow, white, green or red flesh, with equally varying skin color)
- Plums for fresh market are hand harvested, and require 2-4 pickings for optimal maturity over a 7-10 day period. Plums for canning/drying are mechanically harvested by shake and catch methods.
- Japanese plum varieties are predominantly marketed as fresh fruit in the U.S. while European plum varieties have much wider uses. In California, almost all European plum varieties are dried for prunes. In 2011, California was the lead producer of plums, followed by Oregon, Washington, Idaho and Michigan.
- Plumcots/apriplums - Natural plumcots/apriplums have been known for hundreds of years from regions of the world that grow both plums and apricots from seed.
- Pluots - Pluots show more plum than apricot characteristics. The fruit's exterior has smooth skin closely resembling that of a plum. Pluots include some very late-ripening varieties.
- Apriums - Apriums show more apricot traits and flavor than plum. Apriums resemble apricots on the outside. The flesh is usually dense and apriums are noted for their sweet taste. Apriums are usually only available early in the fruit season like apricots. The fruit is gold, with red coloration. Semi- mature fruit is hard and does not ripen if picked before completely mature.
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