Development of chitosan based edible films: process optimization using response surface methodology

Three-factors Box-Behnken design of response surface methodology (RSM) was used to optimize chitosan level (1.5, 2.0, 2.5 %w/v), glycerol level (0.5, 0.75, 1.0 %w/v) and drying temperature (35, 40, 45 °C) for the development of chitosan based edible films. The optimization was done on the basis of different responses viz. thickness, moisture, solubility, colour profile (L*, a*, b* value), penetrability, density, transmittance and water vapor transmission rate (WVTR). The linear effect of chitosan was significant (p < 0.05) on all the responses. However, density was only significantly (p < 0.05) affected by glycerol in a negative linear fashion. Drying temperature also significantly (p < 0.05) affected thickness, penetrability, transmittance and WVTR in linear terms. The quadratic regression coefficient of chitosan showed a significant effect (p < 0.05) on moisture, solubility and WVTR; glycerol level on moisture, L* value and transmittance; and drying temperature on a* value, penetrability, transmittance and WVTR. The effect of interaction of glycerol x temperature as well as chitosan x temperature was also significant (p < 0.05) on a* value and WVTR of edible films. The optimized conditions were: 2.0 % w/v chitosan level, 0.75 % w/v glycerol level and drying temperature 40 °C at a constant time of 48 h. All the response variables were in favourable range including thickness; 108.59 mμ, penetrability; 16.41 N, transmittance; 75.60 %, WVTR; 0.00174 g/m(2)-t for the optimized edible film. Results concluded that edible films with desirable bio-mechanical properties can be successfully developed and effectively utilized in the food packaging industry.