Walnut

, 1702) A walnut is the edible seed of any tree of the genus Juglans (family Juglandaceae), most often the Persian or English walnut, Juglans regia. They are accessory fruit because the outer covering of the fruit is technically an involucre and thus not morphologically part of the carpel; this means it cannot be a drupe but is instead a drupe-like nut. After full ripening, the shell is discarded, and the kernel is eaten. Nuts of the eastern black walnut (Juglans nigra) and butternuts (Juglans cinerea) are less commonly consumed.

, 1702)]] A walnut is the edible seed of any tree of the genus Juglans (family Juglandaceae), most often the Persian or English walnut, Juglans regia. They are accessory fruit because the outer covering of the fruit is technically an involucre and thus not morphologically part of the carpel; this means it cannot be a drupe but is instead a drupe-like nut. After full ripening, the shell is discarded, and the kernel is eaten. Nuts of the eastern black walnut (Juglans nigra) and butternuts (Juglans cinerea) are less commonly consumed. ==Production== In 2023, world production of walnuts (in shell) was four million tonnes, with China contributing 35% of the total (table). Other significant producers (in the order of decreasing harvest) were the United States, Iran, and Turkey. The Livermore cultivar is a red-kernel English walnut developed in California and marketed as a specialty variety. ==Nutrition== English (or Persian) walnuts without shells are 4% water, 15% protein, 65% fat, and 14% carbohydrates, including 7% dietary fiber (table). In a reference amount of , walnuts provide and rich contents (20% or more of the Daily Value, DV) of several dietary minerals, particularly manganese at 148% DV, along with significant amounts of B vitamins (table). Unlike most nuts, which are high in monounsaturated fatty acids, walnut oil is composed largely of polyunsaturated fatty acids (72% of total fats), particularly alpha-linolenic acid (14%) and linoleic acid (58%), although it does contain oleic acid as 13% of total fats (table source). ==Allergic potential== Walnuts are among several tree nuts that have the potential to cause allergic reactions when eaten or if their oils contact the skin. Lifetime walnut allergies occur in about 0.4% of the population in Europe and the United States, although regional prevalence may vary according to availability of walnut products and consumption amounts. The prevalence of walnut and other nut allergies may be as high as 5% in American children. Proteins implicated as allergens in walnut and tree nut allergic reactions include lipid transfer protein, 2S albumin, vicilin, legumin, and oleosin. Symptoms of a walnut allergic reaction are abdominal pain, cramps, nausea, vomiting, difficulty swallowing, itching, shortness of breath, and potentially anaphylaxis, which may be fatal. Walnuts are considered to be a priority food allergen in Canada. Emergency treatment for anaphylaxis includes an injection of epinephrine, while milder symptoms are treated with an antihistamine. An allergic reaction to walnuts is best avoided by not eating or touching walnut products. Walnut allergy is usually lifelong and there is no cure. Walnut allergy appears to have cross-reactivity with the allergies to pecans, cashews, and other tree nuts. ==Uses==

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