Effect of glycerol and sorbitol concentrations on mechanical, optical, and barrier properties of sweet potato starch film

The search to improve the characteristics of biomaterials obtained from natural biopolymers such as starch has led to the use of mixtures of various polymers with plasticizing agents such as glycerol and sorbitol. In this research, the effect of concentration (10, 20, 30, 40 and 50% starch basis) and type of plasticizer (glycerol and sorbitol) on water solubility (WS), total color difference (ΔE), mechanical properties and water vapor permeability (WVP) of films based on sweet potato starch was evaluated. The mechanical properties were determined by the Puncture Strength method, WVP and WS were performed using gravimetric methods, ΔE was determined by a colorimeter. The results showed an inverse relationship between the puncture resistance and ΔE of the films with the concentration of the plasticizers. However, an increase in plasticizer concentration led to an increase in the percentage of elongation, WS, and WVP of sweet potato starch films. The highest values for percentage elongation and WVP were found in films plasticized with glycerol. Sweet potato starch can be used for the development of film for edible candy wrappers and edible coatings fresh fruit and vegetables.