Evaluation of factors affecting barrier, mechanical and optical properties of tragacanth gum-based edible films using Response surface methodology

Emulsion coatings were formulated and films were developed using tragacanth gum as the basic structural component. Preliminary experiments were carried out to determine the proper concentration of tragacanth gum، lipid and plasticizers in the film. The effects of different concentrations of tragacanth gum (0. 65، 1، 1. 5، 2، 2. 35 g /g distilled water)، canola oil (23، 30، 40، 50، 58 g/g tragacanth dry wt basis) and glycerol (33، 40، 50، 60، 67 g/g tragacanth dry wt basis) on water vapor permeability (WVP)، mechanical properties and opacity (OP) of the films were evaluated using the response surface methodology. WVP was observed in the range of (2. 05-36) x 10-11 and increased by tragacanth and glycerol concentration and was decreased by oil concentration. Tensile strength and elongation at break ranged between 0. 67-7. 15 Mpa and 1. 99 – 7. 8%; respectively. Increasing the amount of tragacanth gum and decreasing the glycerol and oil concentration increased tensile strength (TS) while elongation at break (EB) increased by increasing both tragacanth and glycerol concentration and decreased by increasing oil concentration. Oil was the most influential factor that affected opacity، which increased with increasing oil concentration. Models developed for WVP، EB، TS and OP had high coefficient of multiple determination (R2) values (0. 983، 0. 952، 0. 824، 0. 94) respectively.