Potato grading is the sorting of tubers by size, shape and defect status to produce uniform lots suited to specific end uses such as frying, dicing or retail packing, with size ranges expressed in millimetres and defined per buyer specification or market standard.
In trade practice
Grading lines use roller or sieve separators to sort tubers into size fractions, and optical or manual inspection removes defective tubers including those with green patches, rot, mechanical damage or sprouting. Buyers for frozen processing typically specify tight size windows to ensure even cooking and consistent cut dimensions. A common error is grading at harvest without accounting for weight loss during storage, which can shift tubers below the minimum size by the time of processing.
In a specification
A specification should state the minimum and maximum tuber diameter in millimetres, the permitted tolerance for out-of-grade tubers and the defect categories and maximum allowances applicable at intake.