Production of egg white hydrolysate by digestion with pineapple bromelain: optimization, evaluation and antioxidant activity study.

Chicken egg white is known to be an excellent
source of good quality proteins to make hydrolysate with
potential bioactive properties. Enzymatic digestion is a
well-known method to produce protein hydrolysates;
however, the type of enzyme determines the bioactive
potential of the protein hydrolysates due to difference in
their catalytic specificity. In this study, process optimiza�tion, production and evaluation of whole egg white protein
hydrolysate (WEWPH) using pineapple bromelain through
the Box-Behnken design were carried out. The design
experiment (r
2 = 0.9557) displayed a significant (p \0.01)
effect of pH of egg white (9.0), hydrolysis time (24 h), and
enzyme/substrate ratio (3.2 unit/g substrate) on hydrolysis
and to form bioactive WEWPH. Antioxidant activity of the
WEWPH was confirmed by DPPH radical scavenging
assay. Gel filtration chromatography, SDS-PAGE and
FTIR spectroscopy analysis of WEWPH revealed the
digestion of egg white and the integrity of WEWPH in
terms of secondary structure. The WEWPH exhibited
strong scavenging activities of DPPH (EC50 = 238.3 lg/
ml), ABTS ABTS (EC50 = 54.9 lg/ml), peroxyl (EC50-
= 391.6 lg/ml) and superoxide radicals. The WEWPH
also displayed reducing power and singlet oxygen
quenching activity. These results reveal that the bioactive
WEWPH could be a promising ingredient in health food
and nutraceuticals.