Carboxymethyl cellulose-based intelligent modified atmosphere film with humidity monitoring and selective gas permeation for strawberry preservation.

Modified atmosphere packaging (MAP) is an effective technology to prolong the shelf life of fruits by regulating the gas composition inside the packaging. Unfortunately, traditional MAP is limited by the intrinsic defects in materials, making it difficult to control accurately permeation of CO2 and O2 and monitor humidity in storage environment according to the dynamic characteristics of fruit respiration metabolism. Here, we innovatively developed a curcumin@ZIF-8/carboxymethyl cellulose (Cur@ZIF-8/CMC)-based intelligent MAP that integrates both intelligent control and real-time humidity monitoring function. Thanks to the dual sensitivity of ZIF-8 to temperature and pH, the film successfully constructs a controllable gas "switches" function by regulating the stimulus response release of Cur to achieve precise control of CO2/O2 selectivity (3.12-4.15). Simultaneously, Cur@ZIF-8/CMC has real-time humidity monitoring capability and can dynamically perceive humidity changes in the storage microenvironment. Furthermore, the film exhibits outstanding photodynamic antibacterial properties against Escherichia coli (99.75%) and Staphylococcus aureus (99.34%), which were 11.30% and 3.00% higher than those in dark conditions, respectively, achieving effective sterilization in different scenarios, thereby extending the shelf life of strawberries. Note that the excellent biodegradability and biosafety of this intelligent MAP effectively avoid the hidden dangers of environmental pollution and food safety.