An approach to mass produce peppermint oil-sodium alginate composite microcapsules by drop-on-demand system loaded with stabilized nanoemulsion

Microencapsulation technology has found widespread applications in current fields of food industries. In this study, by combining water-in-oil emulsion with drop-on-demand (DOD) technique, we successfully produced sodium alginate (SA) shell microcapsules containing peppermint oil (PO). Response surface methodology (RSM) was employed to optimize the surfactant used for nanoemulsification. A comprehensive investigation into the morphology, structure, and encapsulation efficiency of resulting microcapsules was conducted. The study revealed that various parameters, especially of Hydrophilic-Lipophilic Balance (HLB) values, can affect the physical properties of PO/SA nanoemulsion. The optimized formulation achieved emulsions with a mean droplet size of 46.60 nm. Microcapsules with different shell/core ratios (2, 1, and 0.5) were prepared by pulse duration of 20 ms, exhibiting varying antibacterial activities against Escherichia coli in subsequent tests. This work confirms the feasibility of nanoemulsion-DOD system, highlighting the potential of PO/SA microcapsules as a more environmentally friendly alternative to conventional antimicrobials. This new abstract should be 148 words, less than the 150-word requirement.