Peanuts are graded using guidelines established by the U.S. Department of Agriculture (USDA). Farmer stock peanuts are sampled using a pneumatic sampler. This sample is checked for the amount of: foreign material, loose shelled kernels (not in a pod), kernel size, kernel damage, and moisture. When grading is complete, the overall quality and value of those peanuts has been established. Each wagon, or box if removed from warehouse, is individually graded.
The USDA has set acceptable limits for aflatoxin in shelled peanuts. All peanuts are chemically checked for the presence of aflatoxin. Lots shown to contain # 15 ppb of aflatoxin are acceptable for use in food for humans. Those rejected can be used to obtain peanut oil, which upon processing is aflatoxin-free.