Optimization of the moisture content, thickness, water solubility and water vapor permeability of sodium alginate edible films

摘要

The present study focuses on the effects of concentrations of sodium alginate (0.5-2.5% w/v) and glycerol (0.5-1.5% w/v) and the film forming method (FFM) (dry and wet) on the moisture content, thickness, water solubility, and water vapor permeability (WVP) of edible films. The effects were analyzed using a two-level factorial design. Prediction equations were obtained and optimized for each response variable. To generate insoluble polymers 2% of CaCl_2 was added directly to the film emulsion (wet method). For the dry method, the emulsions were dried at 60 °C for 6 hours, and then CaCl_2 was added. The moisture content, thickness, and water solubility were significantly affected (p < 0.05) by principal effects. Furthermore the glycerol did not affect the water vapor permeability. The films obtained by wet method, showed the highest water solubility values 66.06% (0.5% alginate-glycerol) and WVP 579.74 g mm/kPa h m~2 (2.5 - 0.5% glycerol alginate). Unlike, the films formed by the dry method, the water solubility was 44.66% and WVP was 13.66 g mm/kPa h m~2 for the 0.5 - 1.5 and 2.5 - 0.5% alginate-glycerol concentrations respectively. Predictive equations for each response variable showed a good fit of the experimental data (R~2> 0.999).