Mechanical and Barrier Properties Optimization of Carboxymethyl Chitosan-Gelatin-Based Edible Film Using Response Surface Methodology

Edible coatings have attracted the attention of researchers in recent years due to their degradability, safety, non-toxicity, low cost, good preservation effect, and other advantages. To prepare a new edible film with good mechanical and barrier properties, carboxymethyl chitosan (CMCS) and gelatin (GL) were selected as the film-forming matrix in this experiment, and glycerol, CaCl2, Tween-20, and ascorbic acid (AA) have been added as plasticizers, crosslinking agents, surfactants, and antioxidants. Crosslinking agents and antioxidants first, the film was prepared by the casting method, and single factor tests were used to compare the effects of different CMCS: GL (w:w), glycerol, CaCl2, Tween-20, and AA on mechanical properties (Tensile Strength (TS), Elongation at break (EAB)) and barrier properties (Water Vapor Permeability (WVP), Oxygen Permeability (OP)). Then, the weighting of each performance index is determined by a combination of principal component analysis and the comprehensive membership evaluation method. The formula for calculating the overall rating of edible film performance was determined. Finally, the manufacturing process of edible film with better performance was optimized by a response surface test. The results showed that the influence of each factor on the performance of the edible film was as follows: Glycerol addition > CaCl2 addition > CMCS:GL, Tween-20, and AA had no significant influence on the performance of the edible film. When calculating the overall edible film property score, the weights of TS, EAB, WVP, and OP were 0.251, 0.068, 0.334, and 0.347, respectively. The optimal formulation for an edible film based on CMCS-GL with better properties than pure CMCS and GL film was CMCS:GL = 2:1, with the addition of 1% glycerol, 2% CaCl2, 0.1% Tween-20, and 2% AA. The TS, EAB, OP, and WVP of the film obtained with this formula were: 16.28 MPa, 71.46%, 1.39 × 10−12 g·cm/(cm2·s·Pa), 5.10 × 10−11 cm3·cm/(m2·s·Pa), respectively. This study suggests that CMCS-GL-based edible coatings can be used as a new food packaging material.