Botanical Profile
Juglans nigra is a large deciduous tree of the Juglandaceae native to eastern North America. The species has odd-pinnate aromatic leaves, green fruit husks and hard-shelled nuts. The fruit husks turn intensely brown to black as they ripen and oxidise. The edible kernels have a strong aromatic character, while green fruit husks, leaves, bark and wood each have their own raw-material contexts. Black walnut must be distinguished from Juglans regia, the common walnut.
Phytochemistry
Black-walnut kernels contain fatty oils with unsaturated fatty acids, proteins, minerals, tocopherols and accompanying phenolic substances. Green fruit husks, leaves and bark have different profiles containing naphthoquinone derivatives such as juglone, phenolic acids, flavonoids, tannins and aromatic components. Juglone is significant for oxidation reactions, colouring and the biological activity of the husk fraction, but requires safety consideration. Kernel oil, husk extract, leaf preparation and bark raw material are not interchangeable.
Traditional Uses
Black walnut has a long history in North America as a food, timber, dye and plant raw material. The nuts were used in cooking, while the dark, hard wood was valued for furniture, veneers and crafts. The green fruit husks traditionally served as a dye and also appear in folk plant preparations. Their strong colouring effect is particularly distinctive from a cultural-historical perspective.
Current Research
Research on Juglans nigra addresses nut quality, fatty-acid profiles, wood quality, juglone, phenolic constituents, antimicrobial in-vitro models, allelopathy, plant ecology and extract characterisation. Juglone is studied particularly in connection with the allelopathic effects of walnut species. Food-related research concerns the nutrient profile, allergens and oil quality of the nuts. Data on juglone-rich husk or leaf extracts cannot be transferred to edible kernels.
Sources
- Plants of the World Online: Juglans nigra L.; Royal Botanic Gardens, Kew.
- Specialist literature on Juglans nigra, juglone, fruit husks and kernel oil.
- Food-science and forest-botanical literature on black walnut.
Notice
The information presented in this botanical profile has been compiled to the best of our knowledge and belief from botanical, phytochemical, historical and scientific sources. It is intended solely for general professional information and initial orientation.
The content does not constitute an assurance of specific properties, effects, qualities or possible uses of products or extracts. In particular, it does not constitute a guarantee, a statement of suitability, or a statement regarding marketability, permissibility or usability in specific applications or markets.
Assessment of the suitability of a raw material or extract for a particular intended use, as well as compliance with all applicable legal and regulatory requirements, is the sole responsibility of the respective user.