This study was undertaken to investigate the nanoencapsulation of Zataria multiflora essential oil (ZEO) in chitosan
nanoparticles (CSNPs) in order to enhance antifungal activity and stability of the oils against one isolate of
Botrytis cinerea Pers., the causal agent of gray mould disease. ZEO was encapsulated by an ionic gelation technique
into CSNPs with an average size of 125–175 nm as observed by transmission electron microscopy (TEM). From
UV-vis spectrophotometry results, the drug encapsulation and loading efficiency of ZEO decreased from 45.24%
to 3.26% and from 9.05% to 5.22%, respectively, upon increasing initial ZEO content from 0.25 to 1 g/g chitosan.
In vitro release studies also demonstrated a controlled and sustained release of ZEO for 40 days. The superior performance
of ZEO when encapsulated by CSNPs under both in vitro and in vivo conditions in comparison with unmodified
ZEO against B. cinerea was revealed. The in vivo experiment also showed that the encapsulated oils at
1500 ppm concentration significantly decreased both disease severity and incidence of Botrytis-inoculated strawberries
during 7 days of storage at 4 °C followed by 2–3 more days at 20 °C. These findings revealed the promising
role of CSNPs as a controlled release system for EOs in order to enhance antifungal activities.
Industrial relevance: Application of plant essential oil (EOs) treatment at pre- or postharvest stage has been considered
as an alternative treatment to the use of synthetic fungicides to prevent fruit postharvest decay and to
extend the storage life while retaining the overall quality of different fresh commodities. Although EOs have
proved to be good antimicrobial agents, their use for maintaining fruit quality and reducing fungal decay is
often limited due to their volatile compounds which can easily suffer degradation under the action of heat,
pressure, light and oxygen. Furthermore, they are insoluble in water, and for certain applications a controlled release
is required. In this regard, nano-size carriers provide more surface area and can possibly upgrade solubility,
enhance bioavailability and improve controlled release and targeting of the encapsulated food ingredients, in
comparison to micro-size carriers. These findings revealed the promising role of CSNPs as a controlled release
system for EOs in order to enhance their antimicrobial activities