The thickness of the films was measured using a digital caliper at nin 2 positions to obtain an average thickness. The mechanical properties of PVA-BP extract films – tensile strength, elasticity and % elongation, was characterized by a texture analyser (TA.XTPlus) according to ASTM D882-09, Films were cut into 2.5×10 cm. Neat PVA film was used as a reference for the analysis.
The color stability of PVA-BP extract films will be studied. PVA-butterfly pea extract films will be kept under nitrogen atmosphere, in darkness and ambient condition, for 4 weeks. After that, the color stability of the PVA-butterfly pea extract films will be analyzed by using a colorimeter.