Deciphering the effects of plasticizers in potato-based bioplastic for food and fresh produce packaging.

Abstract

The feasibility of potato-based bioplastics as food or fresh produce packaging materials was investigated using glycerol and sorbitol plasticizers at three different concentrations (30, 50, and 70%). The effects of plasticizers on the tensile strength, water vapour transmission rate, water absorption, and contact angle of the plasticized bioplastic were compared to the pure potato starch-based bioplastic. At same concentration, glycerol-plasticized bioplastic films were more flexible and stickier than sorbitol-plasticized bioplastic films. At all concentrations, however, the tensile strength and elongation at break were consistently lower than the latter. The experimental results revealed that glycerol with a higher hydrophilicity produced bioplastic films with higher water vapour transmission (63.68–80.91%), water absorption (252.65–432.71%), and lower contact angle (36.669°–50.506°) in comparison with sorbitol-plasticized bioplastics. In Fourier transform infrared spectroscopy, the major absorption bands characteristics of all bioplastics, with or without the presence of plasticizers, were found to be identical. A weight loss test on strawberries stored at different temperatures was used to investigate the feasibility of plasticized potato starch-based bioplastics for use as food and fresh produce packaging materials. Increase in the concentration of both plasticizers from 30 to 70% reduced the weight loss of strawberries kept at 4 °C and room temperature, with no significant difference in weight loss observed at the same concentration of the plasticizers. It was also found that when strawberries were wrapped in plasticized bioplastics and kept at 4 °C, water loss was reduced by 4 to 6.8 fold compared to room temperature.