Enzymatic Deamidation of Plant Proteins by Protein-Glutamine Glutaminases: Effects on Solubility, Foaming and Emulsion Properties

Enzymatic deamidation using protein-glutamine glutaminases (PGs) is a promising method for improving the solubility, foaming properties, and emulsifying properties of plant proteins. This study compared the deamidation of various plant proteins using PGs from Chryseobacterium proteolyticum (PGC), Bacteroides helcogenes (PGB), and Flavobacterium sp. (PGF) and examined the effects on the foaming and emulsifying properties of sunflower and oat proteins. PGB produced the largest increases in protein solubility, though PGF usually gave the highest maximal degree of deamidation (DD(max)). For oat protein, all PGs reduced maximum foam volume (VF(max)), but PGC and PGB doubled foam half-time (t1/2 foam). For sunflower protein, PGB reduced VF(max), while PGC increased t1/2 foam by up to 17.5-fold. Thus, different PGs affect techno-functional properties distinctly, reflecting different substrate specificities. Improvements in solubility, foaming, and emulsifying properties are not dependent on achieving the highest DD(max). Expanding the range of available PGs would allow for better matching to plant substrates and enhance industrial applicability.