Formulation and characterization of green tea spent extract incorporated crude tangerine pectin /gelatin active packaging film

Abstract

Biopolymeric materials hold promise as sustainable alternatives to petroleum-derived products in food packaging. Active edible packaging film was developed using pectin and pectin-gelatin composite material integrated with green tea spent extract powder (GTSE). Different formulations consist of pectin (P), pectin-tea phenol (PT), pectin-tea phenol-Ca^{2 +} ion (PT-Ca), pectin: gelatin (PG; 1:1), pectin: gelatin-tea phenol (PTG), and pectin: gelatin--tea phenol-Ca²⁺ ion (PTG-Ca). The structural, mechanical, and functional (antioxidant and antibacterial) properties of all prepared films were measured. Scanning electron microscopy and Fourier transform infrared spectroscopy revealed that the film components were well-organized and that the GTSE was well-dispersed in the matrix via hydrogen bonding. The addition of GTSE significantly enhanced the antioxidant activities of P-film from 44.5 % to 93.1 % while P/G film from 31.9 % to 89.1 % DPPH radical scavenging activity. Whereas, all films were active against only Gram-positive (B. subtilis) bacteria, with the highest inhibition zone of 15.7 ± 2.31 mm for the PT film. The addition of tea phenol decreased the transmittance of the film from 60 % to 45 %. The addition of the tea phenol and calcium ion showed decreased tensile strength and elongation at break (EAB) from 35.5 to 23.7 MPa and 8.12–4.77 %, respectively. The results indicated that the addition of gelatin to pectin enhanced the elasticity and increased the elongation break; however, further addition of tea phenol and Ca ion reduced elasticity, making the film rigid. Therefore, active film formation with pectin-tea phenol-Ca²⁺ ion is recommended for active packaging purposes.