World hazelnut, or filbert, production is based entirely on selections from the wild.
Worldwide, there are nearly 400 distinct, named cultivars, although fewer than 20 of these are worthy of planting for commercial production.
Although a few amateurs have selected large-fruited types from open-pollinated seedlings over the years, breeding programs to develop new and improved cultivars were not established until the 1960's in the U.S., Italy, France, and the 1970's in Spain.
The tremendous amount of genetic variability in the European hazelnut, Corylus avellana L., and 8 related species, remains virtually untouched.
Demand for this delicacy far exceeds current world production and new cultivars are urgently needed.
Hazelnuts have multiple uses and are sold on two different markets - the in-shell market and the kernel market.
Cultivars suited for one use are quite different from those suited for the other.
For the in-shell or whole nut market, with peak sales occurring between Thanksgiving and Christmas, large nuts with attractive shells are required.
Pubescence on the shell is not desirable, as it makes the nuts appear dull.
A minimum of fiber on the kernel is also highly desirable.
The in-shell market accounts for 5 to 10% of the world hazelnut crop.
The remaining 90 to 95% of the crop is cracked and the kernels are sold to bakers, candy makers, and other processors.
The kernels are sold either blanched (pellicle removed) or unblanched.
The ideal cultivar for the blanched kernel market has small, round nuts with thin shells, and crisp-textured kernels from which the pellicle can be easily removed by dry heat.
The round, plump, bright white kernels which result from the blanching process are used for many candies and baked goods, hazelnut butter, and in mixing with chocolate to form a paste called ‘nutella’. Unblanched kernels are commonly roasted and mixed with other nuts for sale as a snack item.
Additional uses are in breads, pastries, and breakfast cereals.