Studies on antioxidant activities of extracts from peel and leaf of mandarin and determination of mechanical properties of coated kraft paper by the extracts

In this study، the possibility of coating of paper using non-aqueous extracts obtained from peels and leaves of mandarin has been investigated. The extraction was carried out using non polar solvents (hexane، chloroform، dichloromethane، petroleum ether) at room temperature. The antioxidant activities of the extracts were determined using DPPH as free radical scavenger. Coating of the kraft paper was performed by its immersion in the extract solutions and evaporation of the solvents. The results showed that hexane-chloroform (1:1 v/v) system was the best solvent for the extraction and coatings. The weight of coated paper increased with an increase in concentration of extracted materials. The mechanical properties of coated paper (Tensile Strength، Young modulus، Elongation at Break) decreased in comparison with uncoated paper. The extracted materials obtained from peel- leave were stronger than that of extracted materials from the peel. The antioxidant activities of both extracted materials were weaker than that of BHA. In conclusion، the extracted materials from peel and peel-leaves caused to a oily coating layer on the paper. Such coating layer with antioxidant properties has potential to be employed in active packaging، but results in a reduction in mechanical properties of the paper.