Physicochemical characterization of antioxidant film based on ternary blend of chitosan and Tulsi-Ajwain essential oil for preserving walnut.

This study focuses on changes in the physiochemical properties of chitosan film when incorporated with a blend of essential oils of Tulsi and Ajwain. The essential oil blend-loaded films showed a decrement in transparency. Tulsi essential oil decreased the moisture content, swelling capacity, and water solubility. However, adding Ajwain along with Tulsi essential oil led to a significant increase in these properties. Meanwhile, the water vapor transmission rate didn't change significantly due to non-polar constituents in Tulsi essential oil, except when only Ajwain essential oil was present. The mechanical properties showed that the tensile strength of films increased with the addition of Tulsi essential oil (14.95 MPa to 31.27 MPa) but decreased further with increasing Ajwain oil concentration in films (32.13 MPa to 15.89 MPa). On the other hand, an increment in percent elongation at break (8.26 % to 24.02 %) was observed due to the excellent plasticization effect of Ajwain essential oil. Antioxidant activity was observed for the Tulsi essential oil-containing films and increased significantly with adding Ajwain essential oil. Finally, walnuts were packed in the active film. The active film showed better antioxidant activity against the oxidation of oil in walnuts, which the FTIR of the packed product confirmed.