Walnuts are very nutritious and tasty nuts belonging to the Juglandaceae family. The United States is one of the biggest producers of this tree nut, contributing to around 0.57 million tonnes in 2017 (Food and Agriculture Organization of the United Nations). California is the hub for walnut production in the US, with the State accounting for 99 percent of the United States’ walnut production. (University of California Agricultural and Natural Resources).
China is the world’s largest producer, accounting for half of the 3.8 million tons produced in 2017.
The top five walnut producers (total in-shell supply in metric tons) for 2020/21 are:
- China – 1,010,000
- USA – 728,637
- Chile – 141,800
- Ukraine – 109,000
- France – 39,000
The above data is sourced from the California Walnut Board and Commission, Ukraine Walnut Association and other bodies.
Walnut sizes and colors
The California shelled walnuts come in a variety of sizes and have different color grades. A list of sizes is below:
- Pieces and halves
- Medium pieces
- Small pieces
- Meal/double diced: This is the smallest avatar of the California walnut and the consistency ranges from a coarse meal to a fine powder. While the meal is used in doughs and batters, the finely ground nuts are incorporated in pastas, added to filling and serve as a thickening agent in sauces and curries.
The walnuts in the color spectrum serve specific product needs and the different shades are:
- Extra Light
- Light Amber
More about walnuts
Some of the walnut's cousins include cashews, pistachios, hazelnuts, pecans, pine nuts, macadamia nuts, and brazil nuts. An edible seed of a drupe, walnuts’ most common variety is the English walnut.
The Latin name of the English walnut is Juglans Regia, which translates to ‘Jupiter’s Royal acorn’. There are two common varieties of the walnut: the English Walnut and the Black Walnut.
The English walnut, also known as the Persian walnut, originated in Iran while the black walnut is native to North America. The English Walnut, however, is more popular in North America because the Black Walnut variety is not commercially developed owing to its hard shell and poor hulling characteristics.
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History of the walnut
Walnuts date back to nearly 7,000 BC, making them the oldest tree in human civilization. The nuts in ancient Iran, historically known as Persia, were reserved for royalty and were traded in the silk route that connected the Middle East with Asia.
While England never grew these Persian walnuts commercially, their traders transported the nut to many parts of the world. This is why the nuts got their name “English walnuts”.
When were Walnuts first grown in California?
Walnut cultivation in California dates to the late 1700s and thanks to the warm climate of the US State, the trees flourished in the west coast of the United States. Commercial planting of the English walnut tree in California began around 1867, and the person responsible for it was an orchardist in the Santa Barbara County town of Goleta named Joseph Sexton (California Walnuts).
The trees were predominantly planted in orchards in the southern parts of the state but gradually moved towards the central and northern parts of the State. At present, the majority of the state’s walnut production happens in the central valley thanks to ideal growing conditions of the region, such as mild weather and fertile soil.
Harvesting and processing
The journey from sapling to tree, and then finally to fresh and delicious nuts is a long one for the English walnut.
When is the peak harvesting period for Walnuts?
It takes between five and seven years for a sapling to grow into an adult tree that will yield a healthy produce. The trees are harvested from late August until around end-November. Farmers use mechanical shakers to shake the tree and detach the walnuts onto the ground.
Once the fallen nuts are collected their outer green husk is removed and the nuts themselves are mechanically dehydrated. This is done to protect its quality that will help improve its shelf life during storage.
Proper storage is important as walnuts are susceptible to insect and fungal mold infestations. Fungal infestations could release aflatoxin, which is a potent carcinogen (Transport Information Service). The ideal condition to store the nuts is in the temperature range of 32 to 38 °F and low humidity. If the storage temperature breaches 86 °F and 75 percent humidity, that could lead to spoilage.
Uses of walnuts
Walnuts have a multitude of uses and their scope goes beyond satiating human stomachs.
Non-food uses: Some of their non-food uses include being part of folk medicine. In fact, they are one of the ingredients in the preparation of herbal medicines such as Bach flower remedies, which are known for its supposed positive effects on human health (Wikipedia).
However, Cancer Research UK have cautioned that "there is no scientific evidence to prove that flower remedies can control, cure or prevent any type of disease, including cancer".
Walnuts are also an element in making inks and dyes. Walnut ink, made from the green husk of the nut, usually the black walnut, has been used by historic artists such as Leonardo da Vinci and Rembrandt (source). The ink can produce stains to make paper look older. Walnuts are also used in making fabric dyes and hair dyes for coloring.
Crushed walnut shells are used as cleaning agents as they are low-abrasive and less toxic.
Food uses: The scope of using walnuts in food preparation is almost limitless. For starters they can be eaten in their nut form either raw, toasted or pickled. In fact, pickled walnuts can either be sweet or savory depending on individual taste and requirement.
They are also a popular ingredient in dishes that stretch across the food spectrum. One can make baklava, walnut soup, cakes such as walnut coffee cake or a banana cake, brownies, pies, and even fudge.
Walnuts are used in meat-based dishes as well, with them being an essential ingredient in meat ball or poultry stew, Circassian chicken that uses crushed walnuts and chicken in walnut sauce, among more.
Walnuts are also a very popular flavor in ice creams and are popular option for garnishing some food and salads. Unripe green walnuts are used in the making of Nocino, a dark liqueur tropical to northern Italy.
Nutritional benefit of walnuts
Walnuts have a multitude of benefits what with it being an excellent source of omega-3 fatty acids and having abundant levels of beneficial antioxidants. Consumption of the nuts as part of a healthy diet help in mitigating cancer risks, promoting healthy gut bacteria, effective management of inflammation and more.
For more on the nutritional benefits of walnuts, click here to read our blog on one of United States’ favorite nuts.