Characteristics of bioplastics based on sago starch contain betel (piper betle) leaf extract: Effect of glycerol as plasticizer

Abstract

The presence of glycerol as plasticizer can improve elasticity of bioplastic. Betel (Piper betle) leaf extract contains tannin and flavonoid which both of them take a role in antioxidant, antibacterial, and antifungal. This study aims to investigate the effect of various glycerol as addition in bioplastic based on sago starch (Metroxylon sp.) which includes density, water absorption, and antimicrobial activity. The betel leaf extract is also added in the bioplastic to help the antimicrobial activity. The betel leaf extraction process used the ultrasonication method for 30 minutes using ethanol as a solvent. The betel leaf concentrated extract then is diluted using aquadest with a concentration of 2 g/100 mL (2%) to be applied as an antimicrobial agent in bioplastics. The results show the highest density was 1.515 g/cm3 indicated by the variation of 30% glycerol. The highest water absorption percentage was shown by samples with 30% glycerol addition which was 75,62%. The antibacterial activity showed that the addition of glycerol to bioplastics was able to inhibit the activity of bacteria (Bacillus cereus) with the best inhibition results were shown in variation with 20% glycerol. However, all variation did not show their inhibition with fungal activity (Aspergillus niger).