Development and characterization of active and pH-sensitive films based on psyllium seed gum incorporated with free and microencapsulated mulberry pomace extracts.

Intelligent packaging with a pH indicator has been a hot research topic due to its extra active role compared with traditional ones. Considering the possible toxicity of synthetic pH sensitive pigments, natural pigments are promising alternative indicators. This work aimed to develop and characterize active and pH sensitive films based on psyllium seed gum (PSG) incorporated with free and microencapsulated mulberry pomace extracts (MPE). Compared with PSG control film, PSG-MPE films showed an increase in total phenolic content and DPPH scavenging activity, and decrease in surface hydrophobicity, lightness, and tensile strength. The molecular interactions between PSG and MPE were confirmed by thermal and microstructure analysis. Moreover, PSG-MPE films displayed wide color differences from red to blue at pH 2.0 - 12.0. PSG-based films containing 10% free and microencapsulated MPE demonstrated better overall performance and economy in packaging applications, which could be used as promising active and pH-sensitive food packaging materials.