Physicochemical properties of chitosan edible films incorporated with different classes of flavonoids

Abstract

Chitosan films were prepared by incorporating catechin hydrate (CH), quercetin dihydrate (QDH) and luteolin (LU) at 1, 3, 5 and 10% (w/w of chitosan). The physicochemical properties of the composite films were significantly affected by the type and the concentration of the flavonoids incorporated. All three composite films showed increased tensile strength (TS, 60–240%), elongation at break (EAB, 140–220%), solubility (50–55%), swelling degree (50–55%) thermal stability and opacity with increasing concentrations of the flavonoids up to 5%. However, TS, EAB and the thermal stability declined with further increase in the flavonoid concentration to 10%. The moisture content, luminosity (L), and the white index (WI) of the films declined (18–20%, 5–20%, and 5–30%, respectively) with increasing concentrations of the flavonoids. Fourier transform infrared (FTIR) spectra of the films confirmed interactions between flavonoids and chitosan, which were reflected by the changes in the physicochemical properties of the composite films. Storage of the films at both room (21 °C) and cold (4 °C) temperatures for six weeks caused reductions in EAB and increases in TS (approximately 100–200% and 40–80%). This study demonstrated that incorporating flavonoids at low levels up to 5% can improve the physicochemical properties of chitosan film.

Keywords

• Chitosan
• Packaging film
• Catechin
• Quercetin
• Luteolin
• Physicochemical properties