Treatment of Kraft paper with citrus wastes for food packaging applications: Water and oxygen barrier properties improvement

Hydrophobic materials extracted from citrus wastes, both peel of mandarin fruits and leaf of mandarin trees were used to treat food-grade Kraft paper. The chemical compounds of the extracts were identified by gas chromatography-mass spectroscopy and infrared spectroscopy, and their antioxidant activities were determined using a free radical scavenger agent (2,2-diphenyl-1-picryl-hydrazyl-hydrate, DPPH). Water vapor permeability, air transmission rate, peroxide value, and microstructure of treated and original papers were also determined. The experimental results showed that: (i) most components of the peel or peel/leaf extracts were terpenes; (ii) free volume existed among cellulose macromolecule chains of the original paper, occupied by a part of extract materials, and another part of the extracts was formed a thin layer on the paper surfaces; and (iii) air and water barrier properties and antioxidant activity of the treated papers were improved, indicating that the extracts were efficient materials for food packaging applications.