Abstract:To elucidate the effect of the microstructure of protein and polysaccharide mixtures on the film properties，the mixture of type A gelatin（GE）/hydroxypropyl starch（HPS）was utilized as the model system.This study focused on the phase separation microstructure and film properties of the mixture at different GE/HPS mass ratios（6∶1，5∶2，3∶4，2∶5），as well as the effects of gallic acid（GA）addition.The results demonstrated that the microstructure of GE/HPS6∶1 and GE/HPS5∶2 solutions was HPS-in-GE（HPS forms the dispersed phase，while GE forms the continuous phase），while the microstructure of GE/HPS3∶4 solutions exhibited a bicontinuous phase.The microstructure of GE/HPS2∶5 film-forming solutions was identified as GE-in-HPS（GE forms the dispersed phase，while HPS forms the continuous phase）.Following the incorporation of GA，the microstructure of GE/HPS/GA6∶1 and GE/HPS/GA2∶5 film-forming solutions transitioned to compatible phases.The microphase separation structure significantly reduced the tensile strength of the films.The microstructure of GE/HPS/GA films further influenced the release characteristics of GA，with the release rate increasing markedly when the HPS phase served as the external phase.After adding GA，the film significantly slowed down the browning rate of apples and reduced the weight loss rate of apples.