I'm an insider. There are two ways to open pine nuts, one is physical method and the other is chemical method. Physical opening is not only mechanical opening, but also grain-by-grain opening, which is labor intensive by hand. The other is chemical openness, using chemical substances such as caustic soda (CCTV has a program exposure), and pine nuts with unknown chemical openness are advised to eat less.

Chemically, the bark of pine nuts is even, smooth, beautiful and yellow. The surface of pine nuts with physical openings is rough, unsmooth and black. It's easy to identify.