About Walnuts

Eating walnuts is a tasty way to eat smart and feel satisfied!  A great addition to both sweet and savory foods, this versatile nut will bring a crunchy richness to a variety of foods and snacks.  Plus, you’ll be getting important nutrients such as Omega-3 fatty acids, antioxidants, dietary fiber, protein and more!

The Central Valley of California is the state’s prime walnut growing region. Its mild climate and deep fertile soils provide ideal growing conditions for the California walnut. California walnuts account for 99% of the commercial U.S. supply and two-thirds of the world supply.

Walnuts are commercially grown throughout the Central Valley of California and in coastal valleys, from Redding in the North to Bakersfield in the South. Current walnut acreage tops more than 200,000 acres.

How Walnuts Grow


After an orchard is planted, it takes approximately six to eight years until its first yield. Constant attention is given to each tree every step of the way — from pruning, spraying and fertilizing to irrigation — to ensure a healthy orchard. Once a walnut tree has been planted and stabilized, it will continue to bear fine quality fruit for as long as a century.

In late August, branches of California walnut trees hang heavy with full, plump walnuts, protected by nature in thick green hulls. The harvest begins in late August when the protective green hulls split, signaling that the nuts are ready to be removed from the trees. Harvesting methods used depend on the size of the orchard and the equipment and crew available to the grower. Harvesting may be done all at one time or over a period of several days. The harvest season usually continues into late November.


Harvesting operations are largely automated. First, the orchard floor is rolled or dragged clean of twigs, rocks and other orchard debris. Then the nuts are removed from the tree by a mechanical shaker. After they have been shaken to the ground, walnuts are swept in rows to allow mechanical harvesters to pick them up for cleaning and hulling.


After hulling and washing, the nuts are transferred from the mechanical harvester into a hopper where they are mechanically dehydrated (air-dried) to the desirable 8% moisture level. This prevents deterioration of the nut and protects its quality during storage. Mechanical dehydration — quick, thorough and scientifically controlled — represents a major improvement over the sun-drying method formerly used.

From this point, the walnuts are off to the packing house!

Source: Walnut Marketing Board of CA

Walnut Processing

From the orchards, hulled walnuts are trucked to nearby packing plants. At this point, the California walnut is destined for different market channels.

Shelled Walnuts 

Clean and dried walnuts are stored in large tanks until ready to be cracked by state-of-the-art equipment to produce what are called shelled walnuts. Only top-quality walnuts enter the processing channels, and all aspects of California walnut processing are done to exceed the world’s highest food processing sanitation and quality control standards.

All walnuts must meet or exceed the standards set by the Walnut Marketing Board, enforced by the Dried Fruits and Treenuts Association of California (DFA). This is your assurance that California walnuts are the world’s finest! Today, about 70% of all walnuts produced in California are marketed as kernels.

Walnuts for both consumer and industrial use are removed from storage as needed and sent to a shelling department where they are cracked. This is done by mechanical cracking machines.

Next, the shelled walnuts are screened, separating kernels into a series of sizes. Then kernels are air separated to remove shell fragments.

By bucket elevator and conveyor systems, the kernels are then moved to electronic color separators and laser sorters. Finally, the walnuts are hand sorted by trained inspectors for quality and are ready for packaging in clear film bags or bulk cartons.


California walnuts are produced in a wide range of sizes, color grades and combinations of sizes and colors to meet the specifications of walnut buyers. Please visit the “Products & Markets” section of the website to obtain specific product information.

Inshell Walnuts

Walnuts with desirable traits such as big beautiful shells, are selected for the inshell market. The walnut is cleaned, dried and readied to be rushed off to markets around the world where Holiday cracking of walnuts is an age-old tradition. Sizing of inshell walnuts is conducted according to USDA standards. Inshell walnuts are sized as either “Jumbo”, “Large”, “Medium” or “Baby.” Please visit the “Products & Markets” section of the website to obtain specific product information.

Storing Walnuts

Cold Storage = Fresh Taste!

You can maintain the fresh taste of California walnuts by keeping them cold. Walnuts go rancid when exposed to warm temperatures for long periods of time. Heat causes the fat in walnuts to change structure, which creates off odors and flavors. Fresh walnuts smell mildly nutty and taste sweet. If your walnuts smell like paint thinner, you know they’re rancid. And if they’re rancid, you should throw them away!

Where to Store Walnuts

When you bring walnuts home from the store, the best place to store them is in your refrigerator or freezer, depending upon when you’re going to use them. If you’re going to use the walnuts right away, place them in your refrigerator. If you’ll be storing them for a month or longer, store them in your freezer.

More Storage and Handling Tips

When storing walnuts in your refrigerator, store them away from foods with strong odors (e.g. fish, cabbage, onions). Walnuts can absorb the flavors of other foods.

One final tip: Wait to shell or chop walnuts until you’re ready to use them. The same applies for ground walnut meal; don’t grind your walnuts until you’re ready to add the walnut meal to your recipe. This will help maintain great flavor.

Source: Walnut Marketing Board of CA

About Nuts