Improved stability and antibacterial activity of cinnamaldehyde emulsion co-stabilized by cyclodextrin glycosyltransferase-catalyzed starch products and Tween 80

Cinnamaldehyde, a yellowish essential oil, has potential applications because of its antibacterial ability but is limited by its instability. In this study, we prepared the microencapsulated cinnamaldehyde emulsion co-stabilized by cyclodextrin glycosyltransferase-catalyzed (CGTase-catalyzed) starch products and Tween 80. Microscopic structure analysis by transmission electron microscopy, inverted fluorescence microscopy, and size distribution determination revealed that additional CGTase-catalyzed starch products could increase their homogeneity and decrease their particle sizes by 67.8%. Fluorescence spectra analysis showed the interactions between cinnamaldehyde and the wall materials with a decrease of 29.2% in fluorescence intensity. The cinnamaldehyde emulsion had good temperature, ionic strength, pH, and storage stability. Time-kill curve and inhibition zone showed increased antibacterial activity. Mechanism analysis by thermal gravimetric analysis and differential scanning calorimetry showed that the emulsion had a dual structure of gel network and cyclodextrin inclusion, contributing to its stability. This study could give new insights into the cinnamaldehyde emulsion and provide a good guidance for its application.