Postharvest - Hazelnut
Corylus avellana L., the filbert or hazelnut is a member of the birch family (Betulaceae). The edible seed is surrounded by a round to slightly oblong shell that must be separated from a husk during or after harvest. All important world cultivars originated from human selections of wild C. avellana in Europe and Turkey. The common name “filbert” originated in England and was originally applied to the long husked types of Corylus avellana to distinguish them from the short husked types, and has since been used in the U.S. to distinguish the cultivated Corylus avellana from other native wild species of Corylus. The common name “hazelnut” is more commonly applied world-wide, for nuts produced by all Corylus species and will be most commonly used in these guidelines.
Two wild species, C. americana and C. cornuta, are found in the U.S. C. americana has been used in breeding programs for crossing with C. avellana in attempts to provide genotypes with sufficient cold hardiness and eastern filbert blight tolerance or resistance to allow production east of the Rocky Mountains with some success. Whatever the chosen common name, nuts from this genera represent one of the world’s major nut crops, second only to almonds (Thompson et al., 1996). Turkey produces most of the world supply (70%), followed by Italy (22%), Spain (5%) and the U.S. (3%). By far the largest production area in the U.S. is the Pacific northwest, with 99% of production occurring in the Willamette Valley of Oregon (Mehlenbacher and Olsen, 1997). Market uses for the U.S. crop has been roughly evenly divided between in-shell and kernel markets, but trends are shifting towards kernel markets. The major variety in the U.S. is Barcelona, followed by Davinia, Ennis and Willamette.