Development of cinnamon essential oil microcapsules with enhanced antimicrobial activity via interfacial crosslinking...

Native starch is difficult to use directly for microcapsule preparation due to its strong hydrophilicity, poor emulsification capacity, and large particle size. This study provides a novel strategy for developing essential oil-loaded microcapsules using Pickering emulsions stabilized by octenyl succinic anhydride (OSA) modified starch nanocrystals (SNCs). The SNCs were prepared via acid hydrolysis of corn starch and further modified with different amounts (3%, 6%, and 12% w/w) of OSA. The SNCs and OSA-modified SNCs (OSNCs) were used to encapsulate cinnamon essential oil (CEO) via interfacial crosslinking in Pickering emulsions, where SNCs/OSNCs (aqueous phase) served as the wall material and isophorone diisocyanate (oil phase) as the cross-linker. The resulting microcapsules (CEO@SNCs, CEO@3%OSNCs, CEO@6%OSNCs, CEO@12%OSNCs) were characterized on physicochemical properties. All OSNC-based microcapsules exhibited superior performance, featuring smaller particle sizes (around 600 nm vs. 2960 nm for CEO@SNCs), higher CEO loading capacity (about 90% compared to 72% for CEO@SNCs), and enhanced long-term stability across a broad temperature range (4-54 °C). Microencapsulation notably improved the functional performance of CEO. In particular, the CEO@6%OSNCs microcapsules demonstrated a release profile consistent with the first-order kinetic model, indicating sustained release behavior, along with effective antioxidant activity and enhanced antifungal efficacy (against B. cinerea and R. stolonifer).