Preparation and characterization of a novel green cinnamon essential oil nanoemulsion for the enhancement of safety and shelf-life of strawberries

This study aimed to optimize a novel green CEO nanoemulsions (CEO NEs) and explore its physicochemical properties and the effect on the shelf-life of strawberries during storage at environmental temperature (20–25 °C). We used CEO as oil phase and tea saponin (TS) as a natural surfactant to formulate the novel green CEO NEs, and its potential as an antimicrobial agent was also investigated. The results showed that CEO NEs had a droplet size about 170 nm with uniform distribution and regularly spherical. These CEO NEs exhibited excellent storage stability, thermal stability, pH stability and centrifugal stability. The antimicrobial test indicated that the minimal inhibitory concentration and the minimal bactericidal (fungicidal) concentration of CEO NEs against Escherichia coli, Botrytis cinerea and Aspergillus flavus were 17.81 μg/mL and 35.62 μg/mL, 35.62 μg/mL and 71.25 μg/mL, 2.23 μg/mL and 4.45 μg/mL, respectively, which were significantly lower than those of pure CEO (333.75 μg/mL and 667.5 μg/mL, 667.5 μg/mL and 1335 μg/mL, 41.72 μg/mL and 83.44 μg/mL). More interestingly, after soaking strawberries in CEO NEs for 2 min, the shelf-life of strawberries can be extended to 7 days at environmental temperature, and a lower rate of weight loss and mildew were showed in the group of CEO NEs than other control groups, especially the strawberries in ultrapure water group went bad first, obviously shranked, and contaminated by molds after 3 days. The above results indicate that CEO NEs prepared in this study has great potential as a new green antimicrobial agent in fruit preservation.