Abstract: The addition of a multifunctional crosslinking reagent, such as glutaraldehyde, to green juice in conjunction with lowering the pH to a value in the range of 3.0 to 5.0, such as by the addition of potassium bisulfate causes substantially complete precipitation of soluble proteins from green juice extracted from leafy plant tissue and simultaneously coagulates suspended protein. The multifunctional crosslinking reagent generally can be any compound having a chemical structure within the following general formula: ##STR1## wherein X is a divalent ion such as oxygen, sulfur or NH; R is hydrogen or a short chain alkyl radical having 1-5 carbon atoms; and n is an integer in the range of 0-10.