Pulse colour sorting is an optical process that removes discoloured, damaged or diseased seeds and residual foreign material from a pulse stream, ensuring the uniform appearance and high purity required by export specifications.
In trade practice
Optical sorters use cameras and air jets to eject off-colour or defective seeds at high throughput. For lentils, beans and chickpeas, buyers typically specify maximum defect counts per kilogram, and colour-sorting results are verified by purity analysis in the inspection certificate. A common mistake is running sorters at excessive feed rates, which reduces rejection accuracy and allows borderline seeds to pass. The step usually follows destoning and cleaning but precedes final grading.
In a specification
A purchase specification may state a maximum percentage of discoloured or damaged seeds by weight, with colour-sorting declared as the method used to achieve that limit.