Comparative studies on properties and antioxidative activity of fish skin gelatin films incorporated with essential oils from various sources

Abstract

Properties of fish skin gelatin films incorporated with three essential oils from various sources (basil, plai and lemon) with a gelatin/essential oil ratio of 1:1 (w/w) were determined. Films containing different essential oils had lower tensile strength and elastic modulus, but higher elongation at break and thickness, compared with the control film (without essential oils) (<em>p</em> < 0.05). Lower water vapour permeability was observed when essential oils were incorporated, in comparison with the control, particularly when basil and lemon essential oils were used (<em>p</em> < 0.05). Films with essential oils had varying <em>L*</em>-, <em>a*</em>-, <em>b*</em>- and <em>∆E*</em>-values (total colour difference) and WI (whiteness). Amongst all films, that incorporated with plai essential oil showed the highest <em>b*</em>- and ∆<em>E*</em>-values but lowest WI (<em>p</em> < 0.05). Lower light transmittance and higher transparency value, indicating more opaqueness, were observed when films were incorporated with essential oils (<em>p</em> < 0.05), especially for film added with lemon essential oil. Film containing basil essential oil showed the highest DPPH and ABTS radical scavenging activities (<em>p</em> < 0.05), whilst those incorporated with lemon essential oil had the highest chelating activity (<em>p</em> < 0.05). Thus, the incorporation of various essential oils from various sources determined properties and antioxidative activity of fish skin gelatin film differently.