Evaluating the effect, type and concentration of plasticizers on properties of edible films made from Charkhak gum

In recent years, biopolymers have been considered as a good replacement for plastic materials from petroleum derivatives in the field of packaging. Therefore, the purpose of this research was to evaluate biodegradable edible films produced by a Persian gum. In this study, Charkhak gum and sorbitol, glycerol and polyethylene glycol 600 were used as plasticizer in four concentrations of 30%, 32/5%, 35% and 37/5% were used to prepare edible films by means of casting approach. Preliminary experiments showed that the Charkhak gum was not blended with polyethylene glycol 600 to form a film with polyethylene glycol 600.The results of ANOVA test demonstrated that an increase in the concentration of plasticizers caused anincrease in oxygen and water vapor permeability and elongation of the films; on the other hand, tensile strength, Young's modulus and surface roughness of the film decreased. Moreover, it was found that water vapor (significantly) and oxygen permeability and extensibility (not significantly) of sorbitol films was lower than glycerol films, however, its surface roughness was more than glycerol films (P<0.05). Thus, considering these parameters, the films containing 30% sorbitol as plasticizer were the best films, because they had the minimum amount of water vapor and oxygen permeability (0.49 g.m/m2/Pa.s and 3.7 respectively) and highest mechanical strength among all films, while having good elongation characteristics.