Tensile properties and antimicrobial activity of bioplastic based on sago starch utilized piper betel leaf

Abstract

Starch has become the most promising source of bioplastic material since it has a low cost, availability, and compostability. Meanwhile, starch-based bioplastic has poor mechanical properties and is not resistant to biological activity. The purpose of this study is to investigate the effect of the addition of antimicrobial from betel leaf extract and plasticizer from glycerol on sago starch bioplastic's tensile properties and antimicrobial activity. The betel leaf extract extraction was done using the ultrasonic method with ethanol 96% as a solvent with a ratio of the betel leaf powder to the solvent 1: 5 (w/v). The sago starch-based bioplastic preparation was done by adding 10 g starch in 100 mL distilled water and was heated at 70 oC for 25 minutes. The different glycerol variation 0%, 10%, 20%, and 30% (%v). and betel leaf extract concentration 0%, 3%, 6%, and 9% (%v) was add to the bioplastic mixture. The disk diffusion method was used to investigate the antimicrobial activity. The bioplastics without glycerol and betel leaf extract showed the highest tensile strength, which was 19.925 MPa. Bioplastic samples showed the highest elongation at break with 30% glycerol variation and 9% betel leaf extract, which was 25.48%. The antimicrobial activity showed that the addition of betel leaf extract with a concentration of 2% in bioplastics could inhibit the activity of bacteria (Bacillus cereus). The highest betel leaf extract composition will increase the bioplastic's ability to inhibit microbial activity.