[Process optimization and quality characterization of freeze-dried powder based on Pickering emulsion of mint...

Mint essential oil(MEO) has been proven to possess various pharmacological activities. However, its practical application in important solid formulations is limited due to its susceptibility to oxidation, volatilization, and degradation, as well as poor stability. To address this issue, this study utilized octenyl succinic anhydride(OSA)-esterified starch as a solid particle stabilizer to construct a mint essential oil Pickering emulsion system(MEO-PE) and achieved solidification of MEO-PE via vacuum freeze-drying. The effects of different types and concentrations of protectants on the physicochemical properties of the freeze-dried powder were evaluated. The results showed that when 8% trehalose was used as the protectant, the prepared MEO-PE freeze-dried powder exhibited the best physical properties, with a recovery rate reaching 83.78%±1.8%. Characterization results from FTIR, XRD, thermogravimetric analysis, and electronic nose all confirmed the successful encapsulation of MEO, with retention rates of menthone and menthol after freeze-drying being 72.09%±0.7% and 83.56%±0.8%, respectively. The in vitro release behaviors of menthone and menthol from the solidified MEO-PE powder both conformed to the Higuchi equation, indicating a sustained-release effect. Different heat treatment results demonstrated that as the temperature increased, the degradation rate of the MEO-PE freeze-dried powder increased, with the half-life significantly shortening from 63 days(25 ℃) to 15 days(60 ℃), exhibiting characteristics of a typical thermal degradation reaction. By combining the Pickering emulsion stabilization system with freeze-drying technology, this study successfully achieved the stabilization and efficient solidification of MEO-PE. This provides a feasible strategy for the long-term preservation and controlled release of MEO in formulations and creates new possibilities for the encapsulation and delivery of volatile oil-based active ingredients.