Hi! What we do is collect the plant material, freeze it immediately in liquid nitrogen and store at -80 ºC. After that, you can grind it whenever you want.
The best way is to keep the leaves cold before extraction. If you have liquid nitrogen, then snap freeze the leaves in liquid nitrogen immediately. Otherwise you can keep them on wet ice prior to extraction for a short time. Another method is to freeze dry the leaf material.
Thank you.. saidi for raising the useful question. Thank you for all the answers. I have a doubt for the storage duration. After cold storage, how long we can store the leaf for protein isolation.