Antioxidant and antimicrobial packaging films developed based on the peel powder of different citrus fruits: A comparative study

Abstract

Citrus is the largest fruit crop planted worldwide. However, the global citrus fruit processing byproducts have not been fully utilized up to now. Citrus peels contain valuable biopolymers and bioactive substances, which are suitable to develop food packaging films. In this study, active packaging films were prepared by directly utilizing citrus peels in their powder form. The films produced from the peel powder of four different citrus fruits (orange, lemon, pomelo and mandarin) were compared for their structural and functional properties. Results showed the four kinds of citrus peel powder contained 16.36%–23.80% pectin, 5.68%–8.23% protein, 3.17%–7.65% lipid, 2.88%–6.27% crude fiber and 11.45–15.47 mg GAE/g polyphenols. Four kinds of citrus peel powder based films exhibited rough surface and transverse with yellow or flesh color. These films had 0.124–0.157 mm of thickness, 18.16%–25.25% of moisture content, 51.98–121.64°of water contact angel, 1.34–1.92 × 10−10 g m−1 s−1 Pa−1 of water vapor permeability, 0.36–0.69 cm3 mm m−2 day−1 atm−1 of oxygen permeability, 8.26–9.14 MPa of tensile strength and 8.05%–17.18% of elongation at break. These films also showed strong antioxidant and antimicrobial activity, which retarded corn oil oxidation. Among the films, mandarin peel powder based film was most effective in retarding oil oxidation due to the excellent light and oxygen barrier capacity and antioxidant activity of the film. Results suggested mandarin peel powder based film was suitable for the active packaging of corn oil.