A pH-indicating intelligent packaging composed of chitosan-purple potato extractions strength by surface-deacetylated chitin nanofibers

The goal of the study is to develop a novel pH-indicating intelligent packaging by using purple potato extractions (PPE), chitosan and surface-deacetylated chitin nanofibers (CN). Since the major pH-sensitive pigment of PPE was anthocyanin (24.3 mg/g), whether anthocyanins could be loaded on a solid phase to prevent its color fading was further tested. The results of Fourier transform infrared spectrophotometry (FT-IR) and differential scanning calorimetry (DSC) indicated that PPE was efficiently attached into the chitosan film. Meanwhile, adding CN (0.450%, w/v) into chitosan film could significantly enhance the tensile strength (TS), the water-resistant ability and the roughness of chitosan film. Whereas higher content of CN (0.600%, w/v) did not further improve mechanical properties and CN would distribute unevenly due to aggregation in the films. In addition to pH-indicating ability, CS-CN-PPE exhibited the extraordinary antioxidant activities and this provides another advantage of packaging readily oxidizable substances. Taken together, the current study provided a novel and biocompatible packaging with strengthened mechanical property and intelligent pH indicator.