4.1. Changes in functional properties of food proteins
Functional properties of proteins connote the physicochemical
properties which govern the behavior of protein in the food
environment [111].
Protein hydrolysis is a powerful tool in the modification of
the functional properties of proteins in food systems, including
solubility, gelation, emulsifying and foaming characteristics. Proteolysis,
besides decreasing the molecular weight, also increases
the number of ionizable groups and can expose hydrophobic
groups, which can change physical or chemical environmental
interactions [112–116]. However, the hydrolysis conditions need to
be controlled to avoid excessive protein hydrolysis that can impair
functionality and cause unfavorable effects, such as production of
bitter-flavored peptides [112].
Protein solubility depends on hydrophilicity and electrostatic
repulsions. Apparently, the improvement of solubility is the most
notable effect on protein functional properties after the hydrolysis
process [108]. Increased solubility of the hydrolyzed protein
is usually due to increase in the number of small peptides, and
the corresponding increase in the ionizable amino and carboxyl
groups. Zhao et al. [116] reported that enzymatic hydrolysis by
Alcalase of an isolated peanut protein improved protein solubility
and this presented a close relationship with the decrease of the