Development of chitosan-based films with invertase enzyme for active packaging: Physicochemical parameters,...

The use of active packaging made from biodegradable polymers can contribute to the environment and to the food industry by increasing the shelf life of their products. This study aimed to produce chitosan-based films incorporated with the invertase enzyme (1, 2, 5, 9, and 10 %) as an alternative to avoid sucrose crystallization in the confectionery industry. The optimum activity of the invertase enzyme was observed at 55 °C and pH 5, thus, the films made with the film-forming solution adjusted to pH 5 and dried at 55 °C were compared with those without pH adjustment and dried at room temperature. Regarding the thermogravimetric analysis (TGA), the greatest weight of loss of the films was observed between 200 and 400 °C, which may be due to the volatilization of moisture from the polymeric films and the depolymerization and pyrolytic decomposition of chitosan. Adjusting the pH and temperature increased the surface roughness and cross-section of the films and increased the elongation at break, solubility (13.38 to 39.50 %), thickness (0.12 to 0.27 mm), and water vapor permeability ratio (2.95 to 8.47 10^-10 g/(m × s × Pa)), in addition to reducing the stiffness and tensile strength. The color parameters were little affected by this change and the insertion of invertase, which acted as a plasticizer, reducing the tensile properties and increasing the flexibility, keeping the water vapor permeability ratio constant. The invertase-based films prevented crystal formation, and the candies exhibited similar or superior physicochemical characteristics compared to those packaged in cellophane. However, a temperature of 35 °C increased water loss. The films demonstrated enzymatic activity and good properties, especially those with pH and temperature adjustments, and may serve as a promising alternative to cellophane for candy packaging in the sugary food industry.