From a botanical point of view, walnuts are large, wrinkled, edible seeds of deciduous trees (Juglans regia). It consists of two halves in a hard shell, which is enclosed in a green husk. However, under commercial conditions, walnuts are rarely sold in their husk. Usually the husk is removed, and the nuts are dried naturally. Walnuts can be sold in shells, which makes up about a third of international trade, or peeled, which makes up the remaining two thirds of international trade in walnuts.
After the shell has been removed, the kernels are checked and sorted, and then they can be sold in various forms, such as halves, quarters or slices. Walnut kernels can be eaten raw or baked as an appetizer, but in Europe they are more often used as an ingredient for home cooking and food production. In recent years, the popularity of walnuts has increased significantly, as their diverse health benefits are promoted in the media.
Basic requirements for the quality of walnuts:
- When walnuts are sold in shells, the shell must be whole and not broken. However, small surface cracks are allowed.
- Both the shell and the walnut shell should be practically free of any visible foreign matter. For inshell walnuts, small pieces of adhered husk are allowed (no more than 10%).
- No insects, mold, rancidity or damage.
- Moisture content: at least 20% for fresh inshell walnuts; maximum 12% for dried inshell walnuts; 5% maximum for walnut kernels.
- Style: Walnut kernels are divided into five categories: halves, chopped kernels (a part comprising at least three quarters of a half), quarters, large pieces and splinters.
- Characteristic taste and no odor or taste.
Special requirements for walnut quality:
- Class – The classification of walnuts is not formally defined in the European Union. However, the classification of the United Nations Economic Commission for Europe (UNECE) is widely used, where walnuts are divided into three main varieties: extra-class, class I and class II. This classification is based on permissible defects. Walnuts are further subdivided into three varieties depending on the color of the kernel.
- Sizes – Walnut classification categories are not formally defined in the European Union. The most frequently used classification of grades is also carried out by UNECE. Dimensions required for Extra Class and Class I, but optional for Class II. For inshell walnuts, the minimum size is 26 mm for Extra Class and Class I. Class II, when the size, has a minimum size of 24 mm.
- Special Features – In practice, quality and price are usually determined by a combination of product style (whole, mixture or pieces), type of kernel, variety and variety. As a rule, higher prices are achieved with the help of light varieties of cores, such as Chandler, and larger sizes.
All products sold in the European Union must be safe, including walnuts. This also applies to imported products. Additives must be approved. Harmful contaminants, such as pesticide residues and excessive amounts of mycotoxins or preservatives, are prohibited. The labels should also clearly indicate whether the food contains allergens.
The incidence of mycotoxins in walnuts is quite low compared to other crops such as peanuts or corn. However, walnuts can be infected with a fungus such as Aspergillus flavus and Aspergillus parasiticus, which thrive in a hot and humid environment. This risk is increased if walnuts remain on the ground after harvesting for too long.
Mold seems to be one of the biggest problems for walnuts. Some studies have shown that the sooner the core has cracked, the more likely it is that mold will develop. The kernels that may be more susceptible to mold are insect-damaged walnuts, tanned nuts, large cracked kernels or shriveled husks and walnuts that have been on the ground for more than two weeks after harvesting.
Since walnuts are quite oily, they may be more prone to rancidity. This happens when the oils in the nut are oxidized, that is, the triglycerides in the nut are exposed to oxygen.
New legislation regarding various changes in pesticide residual limits was introduced in 2018. New walnut residue limits relate to pesticidal fosetil.
Walnut packaging should:
- Protect the appearance, taste, aroma and quality characteristics of the product. Walnut kernels should not be stacked with fibers or fibrous materials, as oil-impregnated fibers accelerate self-heating and rancidity.
- Protect the product from bacteriological and other contamination, including the packaging material itself. When using container shipping, moisture damage may occur if the water content in the cargo is too high.
- Do not give the product smell, taste, color or other extraneous properties, as walnuts are sensitive to unpleasant and pungent odors.
To avoid rancidity, it is important to store walnuts in air- and watertight containers, ideally in cold stores at a temperature of 2–10 ° C and relative humidity up to 70%.
The safety of materials in contact with food should be evaluated to ensure that there is no migration of unsafe levels of chemicals from the material into food.
It is allowed to use materials, in particular paper or stamps with trade specifications, provided that non-toxic ink or glue is used for printing or marking.
Our company strictly complies with the requirements necessary for working in the European market.