Encapsulation, protection, and delivery of natural antimicrobials: Comparison of nanoemulsion, gelled emulsion, and nanoliposomes for food application

The encapsulation of an antimicrobial formulation based on essential oils (EOs) and citrus extract (CE) mixture into nanoemulsion (NE), gelled emulsion (GE), and nanoliposomes (NL) was performed. The encapsulation forms (NE, GE, and NL) were evaluated further for their stability, encapsulation efficiency (EE), controlled release of bioactive ingredients, in vitro and in situ antimicrobial activity. Results showed that all colloidal systems exhibited similar stability behaviors. Among all colloidal systems, NL witnessed the smallest particle size (91.9 nm) with the lowest polydispersity index (0.230) and highest zeta potential (-36 mV) NL has retained the antimicrobial formulation longer, controlled the release over time, and maintained the total phenolic content. The in vitro results showed that GE improved the antimicrobial activity against Escherichia coli, Listeria monocytogenes, Bacillus subtilis, Candida albicans, and Aspergillus flavus. In situ, the test exhibited that GE applied on the bread surface extended the shelf-life and delayed Bacillus subtilis proliferation to 36 days without affecting the sensory properties of baked bread compared to 14 and 24 days in the non-treated group and treated group with sorbate, a chemical additive widely used in bakery products. Consequently, encapsulating natural antimicrobials represents an exciting process that could improve the bioactivity and shelf-life extension of the bread.