Ethanol-induced composite hydrogel based on propylene glycol alginate and zein: Formation, characterization and application

A novel ethanol-induced composite hydrogel was prepared by two edible biopolymers: propylene glycol alginate (PGA) and zein. The effect of pH and different mass ratios of PGA and zein on the properties of the composite hydrogel was investigated. PGA and zein could form a gel induced by ethanol at pH ≥ 3.5, the stability, springiness, hardness and water holding capacity were decreased from pH 3.5 to 5.0. The hydrogen-bonding association was enhanced at pH 3.5 and porous structure was observed. The strength and springiness of the composite hydrogel decreased with increasing concentration of zein until the PGA/zein mass ratio was 5:1. At PGA/zein mass ratio of 5:1, the composite hydrogel exhibited a more elastic and tougher structure than other mass ratios at pH 3.5. Meanwhile, compared with the PGA hydrogel, the PGA-zein composite hydrogel showed great ability to sustain the release of curcumin in simulated gastrointestinal tract conditions.