Chitosan nanoparticles loaded with Cinnamomum zeylanicum essential oil enhance the shelf life of cucumber during cold storage

Abstract

This study aimed to improve the antimicrobial activity and stability of Cinnamomum zeylanicum essential oil (CEO) against Phytophthora drechsleri, the causal agent of cucumber (Cucumis sativus) fruit rot in laboratory media and when applied as a coating on cucumbers. Additionally, the influence of chitosan nanoparticles (CSN)-based coatings on several physicochemical characteristics of the fruit during storage was assessed. CEO was encapsulated by an ionic gelation technique into CSN with an average size of 100–190nm. The encapsulation efficiency (EE) and loading capacity (LC) of CEO-loaded CSNs (CEO-CSN) were about 2–17% and 3–4%, respectively, with the initial CEO content of 0.25–1kg/kg chitosan. In vitro release studies showed a controlled and sustained release of CEO for 40 d. The superior performance of CEO when encapsulated by CSNs under both in vitro and in vivo conditions in comparison with unmodified CEO against P. drechsleri was studied. The in vivo experiment also showed that the encapsulated oils at 1.5g/L concentration significantly decreased both disease severity and incidence of Phytophthora-inoculated cucumbers during 7 d of storage at 4°C followed by 2–3 more days at 20°C. Furthermore, the CEO-CSN coating extended the shelf life of cucumbers up to 21 d at 10±1°C while uncoated fruit were unmarketable in less than 15d. CEO-CSN coating improved the microbiological and physicochemical quality of cucumbers. Coated fruit were firmer, maintained color, water content, and showed lower microbial counts (P<0.05) throughout storage. According to these results, CEO-CSN coatings can be an effective method to extend cucumber shelf life.