Effects of glycerol and sorbitol on a novel biodegradable edible film based on Malva sylvestris flower gum.

There has been an increasing interest in the investigation of novel eco-friendly packaging materials. An edible film based on Malva sylvestris flower gum was fabricated with 40%, 50%, and 60% glycerol and sorbitol using casting method. FTIR analysis was applied to identify the functional groups of films with different concentrations of plasticizers. The lightness of the samples did not affect upon increasing the sorbitol and glycerol; nevertheless, the samples tended to be green and yellow. SEM images indicated that glycerol-based films enjoy heterogeneous and porous surfaces compared to the sorbitol-based samples. Although Tensile Strength and Young's Modulus characteristics declined considerably ( p  < .05) upon plasticizer addition, elongation at break increased by more than 10% in glycerol-based samples. A significant ( p  < .05) decrement was observed in the density of film strips via the addition of glycerol and sorbitol. Moisture content of films incorporated with both plasticizers saw a considerable improvement ( p  < .05) upon increasing the plasticizer concentration from 40% to 60% and is ascribed to the water-holding capacity of plasticizers. Water contact angle and water solubility increased via plasticizer supplementation, which is attributed to the hydrophilic characteristic of glycerol and sorbitol, are in line with SEM analysis.