Physical, antioxidant and antimicrobial properties of chitosan–cinnamon leaf oil films as affected by oleic acid

• Oleic acid improved the barrier properties of chitosan–cinnamon leaf oil (C) films.
• Oleic acid diminished changes in colour and mechanical properties promoted by C.
• Chitosan–C films showed antifungal activity against three fungi.
• Films increased the self-life of strawberries infected with Rhizopus stolonifer.
• Oleic acid addition promoted C retention into the film matrix during film drying.

The physical, antioxidant and antimicrobial properties of chitosan (CH)–cinnamon leaf essential oil (C) films, containing or not oleic acid (OA), were evaluated. The addition of OA led an increase in surface charge and particle size of the film-forming dispersions. This is in agreement with a greater CH adsorption on the droplets containing OA and the entrapment of C compounds in the non-polar core of the OA molecule associations. OA contributed to a better retention of C in the film during its drying, diminished the changes in colour parameters provoked by C addition and reduced the film transparency. Water vapour permeability of CH films was reduced by OA incorporation while it increased when they contained only C. Every film containing C showed antioxidant and antifungal properties, depending on the C content (the higher the C content, the greater the effect). OA reduced the antifungal effectiveness of C containing films in line with its encapsulating effect on C compounds. All the coatings were effective in extending the shelf-life of cold-stored strawberries, mainly when CH was combined with C at the ratio 1:0.5.

SEM micrographs of cross-sections of the films. Magnification is 2000×. CH: chitosan. OA: oleic acid. C: Cinnamon leaf essential oil. Subscripts indicate the ratio of the components in the film.Figure optionsDownload as PowerPoint slide