Evaluation of the chitosan films of essential oils from Origanum vulgare L (oregano) and Rosmarinus officinalis L (rosemary)

Johannes Delgado Ospina, Carlos David Grande, Leidy Vanesa Monsalve, Rigoberto C Advíncula, José Herminsul Mina, Mayra Eliana Valencia, Jingjing Fan, Debora Rodrigues

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Introduction: Recent years have witnessed an increase in the demand for safe materials derived from biodegradable compounds useful to lengthen the shelf life of foods. Chitosan is a biological macromolecule with antimicrobial and antioxidant properties used alone or combined with natural ingredients such as essential oils for its capacity to lengthen the shelf life of foods. Origanum vulgare L. (Lamiaceae) and Rosmarinus officinalis L. (Lamiaceae) are two plants traditionally used in Colombia for medicinal and food purposes due to their bioactive and organoleptic properties.
Objective: Study the mixture of essential oils of O. vulgare and R. officinalis, Colombian varieties with chitosan films, to incorporate the antioxidant and antimicrobial properties of these films and thus prevent the decomposition and deterioration of foods.
Methods: Chitosan films mixed with essential oils were obtained. The essential oils were extracted from leaves of Origanum vulgare L. and Rosmarinus officinalis L. by hydrodistillation and incorporated with the films at concentrations of 0.4 and 1.5 % (v/v). An evaluation was performed of their mechanical properties, total phenolic content (TPC), antioxidant capacity and antibacterial activity against E. coli K-12 MG 1655 and B. subtilis 102.
Results: It was found that incorporation of the essential oils with the chitosan matrix reduces the mechanical properties of the films (tensile strength), increases their opacity (Y) and total phenolic content (TPC), and improves their antioxidant and antibacterial properties.
Conclusions: Results suggest that the presence of rosemary and oregano essential oils may increase the antioxidant and antimicrobial properties of the films, both of which are useful for food preservation. Therefore, they are recommended as a food packaging method. However, further experimentation should consider the forms of interaction between the films and the food item in question to better understand their effect on organoleptic properties.

Key words: antioxidant, antimicrobial, chitosan films, essential oils, Origanum vulgare L., Rosmarinus officinalis L.