Functionalization of chitosan films using essential oils by supercritical CO2 impregnation method for various applications

OPEN ACCESS LINK

Abstract:

Herein, chitosan films obtained by different approaches were functionalized with essential oils, i.e. mentha, clove, and cinnamon, by Supercritical Solvent Impregnation method to impart antioxidant and antimicrobial activity. The films were prepared from solutions with two different polymer concentrations (1 and 2.5 wt%) following three methodologies: casting and then drying at air (25 °C, 39 % relative humidity), casting and drying at 60 °C in humid conditions (82 % relativity humidity) and casting and water elimination by a freeze-drying process. The films were, then, characterized by scanning electron microscopy and X-ray diffraction, proving that the thickness, porosity, and crystallinity of the films are highly dependent on the preparation method. These structural variations affected the impregnation of essential oils by supercritical fluids, in terms of the amount and composition of the active compounds. Subsequently, yellowness, antioxidant and antimicrobial properties of the impregnated films were evaluated. The results demonstrated that the impregnated films retained high concentration of essential oils, especially the films impregnated with clove and produced by the freeze-drying process due to their higher porosity and lower crystallinity. These films also exhibited superior antimicrobial activity against Gram-positive and Gram-negative bacteria in comparison with the other two analyzed preparation methods.

Data from the article:

Figure_1_SEM_of_cross-sections_of_A-CS1_A-CS2.5_O–CS1_O–CS2.5_l-CS1_and_l-CS2.5_films

Figure_2_Value_of_Yellowness_Index_for_impregnated_and_non-impregnated_films _(A)_by_casting_and_(B)_by_lyophilization

Figure_3_Scavenging_activity_of_CS_films_impregnated_with_MEO_CLEO_and_CEO

Table_1_CS_films_prepared_by_different_drying_approaches_and_their_thickness_values_determined_by_SEM

Table_2_Quantitative_essential_oil_impregnated_in_CS_films_in_wt

Table_3_GC–MS_analysis_of_cinnamon_(CEO)_clove_(CLEO)_and_mentha_(MEO)_using_NIST_library_Rt

Table_4_Active_compound_amounts_(percentage)_of_the_CS_films_impregnated_with_MEO_CLEO_and_CEO

Table_5_Antimicrobial_activity_estimated_as_bacterial_reduction_percentage_of_CS_films_with_MEO_CLEO_and_CEO