Peanut Shelling

After proper curing, farmers' stock peanuts (harvested peanuts that have not been shelled, cleaned or crushed) are inspected and graded to establish the quality and value of the product. The inspection process determines the overall quality and on-farm value of the shelled product for commercial sales or price support loans.

The inspection and grading of peanuts by the Agricultural Marketing Service of the U.S. Department of Agriculture (USDA/AMS) occurs at buying stations or shelling plants usually located within a few miles of where the peanuts have been harvested. A pneumatic sampler withdraws a representative quantity of peanuts from the drying wagon, and from this sample, the USDA inspector determines the meat content, size of pods (for Virginia & Valencia), damaged kernels, foreign material, and kernel moisture content. Once the grade is established, the loan or commercial value is determined from USDA price support schedules.

After grading, peanuts move on to the shelling process.  In the first step of this process, peanuts are cleaned -- stones, soil, bits of vines and other foreign materials are then removed.  The cleaned peanuts move by conveyor to shelling machines where peanuts are de-hulled as they are forced through perforated grates. The peanuts then pass through updraft air columns that separate the kernels from the hulls. Specific gravity machines separate the kernels and the unshelled pods. The kernels are then passed over the various perforated grading screens, where they are sorted by size into market grades.

The edible nuts are individually inspected with high-speed electronic color sorting equipment that eliminates discolored or defective kernels as well as any remaining foreign material.

Inshell peanuts are usually produced from large Virginia or Valencia type peanuts that have been grown in sandy and light-colored soil for bright hulls. Sizing screens remove the small pods, while updraft air columns remove very immature and lightweight pods. The largest remaining pods are separated into size categories by screens. Stems are removed, and any remaining immature pods are removed by specific gravity. Electronic sorters then remove dark, cracked, or damaged pods so that only the most mature, brightest pods remain.

All U.S. peanut handlers are obliged to follow the provisions set forth in the Minimum Quality and Handling Standards for Domestic and Imported Peanuts Agreement. This program is administered jointly by The Peanut Standards Board (18 member industry committee) and USDA’s Agriculture Marketing Service (AMS). The Peanut Standards Board recommends the incoming and outgoing quality standards and regulations on all peanuts that handlers buy for commercial use. The Secretary of Agriculture is charged with implementing these recommendations.

Incoming quality standards require all handlers to officially inspect farmers’ stock peanuts and certify them as to mold, damage, moisture content, and foreign material. The outgoing regulations, applied after peanuts are milled, require all peanuts to meet specific quality factors and be analyzed for aflatoxin. Specifications for U.S. peanuts are modified as needed based on developments within the industry.

U.S. standards – administered and overseen by the Peanut Standards Board and USDA/AMS – establish the minimum specifications which U.S. peanuts must meet. Stricter tolerances for certain grades and sizes have also been established by the American Peanut Shellers Association (APSA).

A detailed overview of U.S. peanut grading, sampling and aflatoxin testing at buying points, shelling plants, and USDA-approved laboratories.

APSA Trading Rules