Interaction and phase behavior of whey protein and propylene glycol alginate complex condensates

•PGA could reduce the pH of the maximum turbidity of WP solution.•PGA can improve the stability of WP at the isoelectric point.•The interaction between WP and PGA was the strongest at the ratio of 3:1.•WP and PGA formed soluble complexes at pH 4.6 and the WP/PGA ratio of 3:1.•WP/PGA = 3:1, pH 4.6 can be used as a new encapsulation wall material formula. WP: whey protein; PGA: propylene glycol alginate.