Controlled release active films prepared from temperature responded emulsions and their application in grape preservation

This study constructed a sodium alginate (SA)-based temperature-responsive emulsion film. The addition of 6 % of whey isolate protein fibre (WPF) and glycyrrhizic acid (3:1) prepared stable emulsions and endowed it temperature-responsive release capability at 4–45℃. The incorporation of prepared emulsions (10–50 % v/v) into SA-based films (E-SA) improved the UV-blocking and antioxidant properties, while it decreased the breaking strength and water solubility. Especially, 30 %E-SA film exhibited best elongation at break water vapor barrier performance, and temperature-responsive release capability. In preservation experiments, the 30 %E-SA film had excellent effect on maintaining pH, soluble solids and V C content of grapes. Especially, the weight loss of grape treated with 30 %E-SA film (19.88 %) was reduced by 44.50 % compared to control grapes at 45°C after 6 d. Therefore, the emulsion-based films prepared are expected to provide an attractive method for preserving grape freshness in different temperature environments .