pH-indicative Films Based on Chitosan–PVA/Sepiolite and Anthocyanin from Red Cabbage: Application in Milk Packaging

Biobased smart packaging is been the most interesting research field. In this study, pH-sensitive films based on anthocyanin molecules from red cabbage and sepiolite mineral nano-clay as functional additives were studied. The films were fabricated by casting method of blend polymer Chitosan/Poly (Vinyl Alcohol) at two fillers loading (5wt.% and 10wt.%). The structural, morphological, thermal, optical, hygroscopic, and mechanical properties as well as the pH sensitivity of films were investigated. The thermal properties confirm that the amount of the anthocyanin in sepiolite was around 6.4%. The tensile strength and the young’s modulus of produced composites at 10wt.% sepiolite–anthocyanin content was increased to 8.90 MPa and 163 MPa, respectively. The maximum water absorption that the films may absorb was 12.3%. pH sensitivity analysis showed that the Smart films change the color by changing the pH level, from pink at pH lower than 6 to yellow at pH higher than 6. Thus, the developed pH-sensitive films show band gaps in visible light that make them useful for monitoring milk spoilage.