Halochromic and antioxidant capacity of smart films of chitosan/chitin nanocrystals with curcuma oil and anthocyanins

Curcuma longa L. essential oil and anthocyanin extracts contain bioactive compounds such as antioxidant properties and their pigments are able to change color when exposed to different pH or ammonium gas. In this context, the objective of the present work was to develop pH-sensitive intelligent films by adding curcuma oil (composed of essential oils and pigments) and anthocyanin extracts to a chitosan matrix reinforced with alpha-chitin nanocrystals. The incorporation of curcuma oil, anthocyanins and nanocrystals enhanced the mechanical properties and hydrophobicity; and, decreased water solubility and moisture content. In addition, the films also showed almost total blocking against UV/Vis light at wavelengths below 550 nm. Interestingly, the films were at the same time antioxidant, and sensitive to color change when exposed to ammonia gas and different pH solutions, with greater variations observed when higher concentrations of curcuma oil were added. Hence, these results revealed the potential of these films as intelligent food packaging applications. [Display omitted] •Smart films were developed based on curcuma oil, anthocyanins and chitin nanocrystals.•Curcuma oil and anthocyanins exhibited color changes with pH and volatile ammonia.•Nanocomposite films demonstrated to be a good barrier against UV/Vis light.•Nanocomposite films exhibited good antioxidant capacity and total phenolic content.•Nanocomposite films could be applied in food packaging as quality sensors.