Bionic modified atmosphere film Inspired by plant stomata with curcumin as controllable gas "Switches" for fruit preservation

Modified atmosphere packaging (MAP) is a promising preservation technology for the fruits with the characteristics of respiration metabolism. However, traditional MAP cannot precisely control and regulate the selective permeation of gas. Inspired by the fact that plants control respiration through leaf stomata, we innovatively construct a bionic intelligent MAP of curcumin-porous starch/chitosan (Cur-PS/CS) with leaf stomata structure. Herein, PS is used as the bionic stomata, and Cur is used as the gas switch controlled by changing the pH and temperature. As a result, the CO2/O2 selectivity values are precisely controlled from 2.60 to 5.51 by controlling the amount of Cur released from PS. In which, the 10.3 % Cur-PS/CS displays the highest CO2/O2 selectivity value (5.51). In addition to outstanding tensile strength (51.54 MPa) and antioxidant activity (91.03 %), the inhibition zone diameters of 10.3 % Cur-PS/CS film against Escherichia coli, Staphylococcus aureus and Aspergillus niger reach 8 mm, 7.8 mm and 9.1 mm, respectively. Therefore, the 10.3 % Cur-PS/CS film effectively extends the shelf life of the non-climacteric fruit (cherries) and climacteric fruit (apple slices). More importantly, it does not bring any issues with food safety and environmental contamination due to the excellent biodegradability of Cur-PS/CS film.