Nut storage

HGA recently received enquiries on best practice for storing hazelnuts. Bryan Thomas offered the following advice.

By Bryan Thomas

HGA newsletter October 2010

There can be no doubt that hazelnuts will keep best in-shell provided that the moisture level is reasonably low (4-5%) and the temperature is moderate. Once out of the shell there is potential for contamination from handling, from containers and from airborne material, any of which can initiate deterioration. Such deterioration will proceed more rapidly at higher temperatures and in the presence of moisture.

If un-contaminated, the proteins and oils in the kernel will break down only slowly provided the temperature is low. Therefore the key is to ensure nuts are correctly dried, crack them in a clean environment, using clean utensils and use clean moisture-proof containers, and store at low temperatures (eg fridge). It is also worthwhile washing nuts prior to cracking if there is contamination on the outside of the shells that may get onto the kernel.

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International hazelnut quality characteristics

Niels Maness – Department of Horticulture, Oklahoma State University

HGA newsletter, June 2006

Quality Characteristics and Criteria

In-shell hazelnuts should be properly sized to meet the stated market type and should be properly filled with at least 50% of the shell cavity occupied by nutmeat. Shells should be free of cracks and noticeable mechanical injury, clean, brightly colored and coloring patterns should be characteristic of the stated variety. The pellicle should be smooth and devoid of husk attachments. Kernels should meet the stated market type, be free of any misshapen or underdeveloped kernels and be free of any shell or foreign material and off-odor, off-flavor or mold. Water content of kernels should not exceed 6% if shelled or 7% if in-shell, and the total water content of unshelled nuts should not exceed 10 to 12%. Size is specified with grade as a determinant of quality, and minimum sizes are used for specification of classes “Extra” and “Class I” in international trade. For in-shell markets, larger and particularly rounded types are preferred. Shelled markets accommodate both rounded and oblong types, and size preference is dependent on the intended end use. 

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