Active chitosan/gelatin‐based films and coatings containing eugenol and oregano essential oil for fresh cheese preservation

Abstract

The use of active substance‐containing biodegradable and edible coatings has become a potentially viable alternative for food preservation, especially to retard oxidative processes and the growth of pathogenic and spoilage microorganisms on the surface of the foodstuffs. In this context, the objective of this research was to develop and characterize gelatin (GL)/chitosan (CH)‐based active, biodegradable, and edible films and coatings containing eugenol (EU) and oregano (Origanum vulgare) essential oil (OEO) in different OEO:EU ratios, and obtained via casting for application in fresh cheese. More soluble, wetter, yellower, and opaque films than the control film system were obtained as a consequence of a higher OEO:EU ratio. Although, the water vapor barrier properties in OEO‐containing films were markedly enhanced with respect to control film system. All the films displayed a slight phase separation, but this was more noticeable when increasing the OEO:EU ratio. This could explain the higher moisture content and water solubility values as the OEO:EU ratio increased. The films containing EU and OEO showed antimicrobial activity against Staphylococcus aureus and Escherichia coli. The best film systems were selected and tested as coatings for the preservation of fresh cheese. In particular, the coating F4 (0.5% wt/wt of OEO + 0.5% wt/wt of EU) displayed the best conservation capacity of fresh cheese during 14 days of storage at 4°C. This predominantly through the reduction of the colony‐forming units of S. aureus, total coliforms, and mesophilic aerobic.Practical applicationsThe addition of EU and OEO in CH/GL‐based coatings presented a synergistic effect in terms of their antimicrobial activity. These food packaging materials would be an alternative for the preservation of foods susceptible to contamination by pathogenic and/or spoilage microorganisms during storage. Besides, the addition of OEO improved particularly the barrier properties of active, biodegradable, and edible films, which allows their use as a protection mechanism for high‐moisture and medium‐moisture foods, such as fresh cheese. Overall, assessed coatings could increase the shelf life of fresh cheese in terms of food safety, but not its quality in terms of maintaining its freshness.