Properties and antioxidative activity of fish gelatin-based film incorporated with epigallocatechin gallate

Abstract

Antioxidative activity of epigallocatechin gallate (EGCG) was examined. Effect of EGCG at various concentrations (0–0.20%, w/v) on the properties of fish gelatin-based films was also investigated. EGCG showed 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities, ferric reducing antioxidant power (FRAP), hydrogen peroxide scavenging activity and oxygen radical absorbance capacity (ORAC) of 12.78, 7.68, 11.02, 3.59 and 2.92 mmol Trolox equivalent (TE)/g sample, respectively. Films containing 0.15 and 0.20% EGCG exhibited higher tensile strength (TS) and water vapor permeability (WVP) but lower elongation at break (EAB) and light transmission, compared with the control film (P < 0.05). All films incorporated with EGCG showed higher a∗-, b∗- and ΔE∗ than the control film (P < 0.05). All films had smooth surface. The incorporation of 0.20% EGCG increased glass transition temperature (Tg) of gelatin film. FTIR analysis revealed the interaction between protein and EGCG. Incorporation of EGCG at levels higher than 0.10% yielded more compact films, compared to the control. Higher seal strength and seal efficiency were observed for film incorporated with 0.20% EGCG in comparison with control film (P < 0.05). When the migration of EGCG from gelatin film was tested, the highest release of EGCG was found for film containing 0.20% EGCG after 18 days of storage. Therefore, the incorporation of EGCG having antioxidant activity had the impact on properties as well as heat seal ability of gelatin film. The resulting film could be used as antioxidant packaging material.