**1. Botanical and Chemical Characteristics:**
– Walnuts are single-seed stone fruits ripening between September and November.
– The brown shell encloses the kernel usually in two halves.
– Walnut hulls contain polyphenols like ferulic acid and juglone.
– Ellagitannin pedunculagin is found in walnuts.
– Juglone concentration in walnut husks is 2-4% fresh weight.
**2. Cultivation and Production Statistics:**
– In 2021, global walnut production was 3.5 million tonnes.
– China contributed 31% of the total production.
– Major walnut producers in 2021 were China, the US, Iran, and Turkey.
– China, the US, Iran, and Turkey are significant walnut producers.
**3. Nutritional Value and Health Benefits:**
– Walnuts are rich in nutrients like protein, fiber, and healthy fats.
– A 100-gram serving of walnuts provides 2,740 kilojoules (654 kcal) of energy.
– Walnuts are associated with heart-healthy benefits due to their antioxidants.
– Regular walnut consumption may reduce inflammation and improve brain health.
**4. Uses in Various Industries and Cultural Significance:**
– Walnut husks can be used to make durable ink for writing and drawing.
– Crushed walnut shells are used for cleaning in non-aviation applications.
– Walnuts have been used in traditional Chinese and Bach flower remedies.
– Carved walnut shells are collectibles and status symbols in China.
**5. Regulatory Information and Research Findings:**
– The FDA has issued warnings and enforcement actions related to walnut health claims.
– Studies suggest walnuts may help maintain normal blood LDL-cholesterol levels.
– Meta-analyses indicate walnut intake may have positive effects on blood pressure.
– The European Food Safety Authority has provided opinions on health claims associated with walnuts.
A walnut is the edible seed of any tree of the genus Juglans (family Juglandaceae), particularly 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.