Preparation of Chitosan-Based Composite Response Membrane and Its CO2 Response Behavior

The intelligent packaging freshness indicator materials have the function of monitoring food quality. Chitosan has been found many applications due to its unique properties, but its use as a freshness indicating material is rarely reported. To extend the application of chitosan in food packages and solve the problem of testing food safety, we have prepared a composite response membrane using N-succinyl chitosan (NSCS) and hydroxypropyl chitosan (HPCS) as film-forming material, with methyl red-bromothymol blue as an indicator by the tape casting method. The results show that the optimum technical conditions of the composite membrane are as follows: 0.5 of HPCS/NSCS mass ratio, 10% of glycerol, 2% of indicator, and 4.0 mL of solution volume. The composite response membrane has a good response behavior of CO2, and is expected to indicate the freshness of fruits.