Tara gum/polyvinyl alcohol-based colorimetric NH3 indicator films incorporating curcumin for intelligent packaging

Curcumin (Cur) was incorporated into a tara gum and polyvinyl alcohol (PVA) blended matrix to prepare an intelligent film. The film was characterized by Fourier transform-infrared spectroscopy and scanning electron microscopy (SEM). The results revealed a hydrogen bonding interaction between curcumin and the matrix; the addition of Cur loosened the film structure as shown from the SEM images. The effects of adding Cur on the mechanical properties, barrier properties, optical properties, surface wettability and thermal stability were also tested. As the Cur content increased from 0.1% to 0.5%, the light transmittance of the film at 600 nm decreased slightly from 32.90% to 27.45%; the oxygen barrier properties of the film also decreased, but the surface wettability increased from 98° to 103°. The response of the intelligent film in an NH3 environment under different relative humidities was studied. A color response in the NH3 environment was visible within 1–3 min. Moreover, higher relative humidity was favorable for a color response. A shrimp spoilage test was conducted to evaluate practical application of the film, and an obvious change was observed, indicating the film could be used as a sensor in the food industry.