Method of cleaning milk thistle seeds from hard-to-separate impurities

Milk thistle is a priority medicinal herb. Freshly harvested milk thistle seeds in 2025 were contaminated with seeds of sage grass, white goosefoot, rough knotweed, bindweed, and wild oats. It is difficult to separate bindweed and wild oats from the seeds of this herb. Bindweed particles are short impurities in herb seeds, and they are separated from seed material by passing through a cylindrical separator with working elements with 4.5 or 5.0 mm mesh size. Fine particles of wild oats are separated from grass seeds by passing through holes of sorting sieve, and the remaining impurities are separated from seed material as long impurities by passing through a cylindrical separator with working elements with 9.0 or 9.5 mm mesh sizes. In general, a method has been developed for cleaning seeds of milk thistle from hard-to-separate impurities.