Title: Influence of disperse phase characteristics on stability, physical and antimicrobial properties of emulsions containing cinnamaldehyde Authors
Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 17, 2012
Publication Date: November 2, 2012
Citation: Bilbao-Sainz, C., Chiou, B., Du, W., Gregorski, K.S., Orts, W.J. 2012. Influence of disperse phase characteristics on stability, physical and antimicrobial properties of emulsions containing cinnamaldehyde. Journal of the American Oil Chemists' Society. 90:233-241. DOI: 10.1007/S11746-012-2164-1. Interpretive Summary: In the last years, there has been an increased interest in the use of cinnamaldehyde as a natural antimicrobial agent due to its antibacterial activity against a number of gram-positive and gram-negative bacteria. However, direct incorporation of cinnamaldehyde to formulations might encounter technological limitations due to its high volatility and low water solubility. An alternative approach to increase the physical stability of this bioactive compound involves encapsulation technology. Among the different encapsulation systems, emulsion-based ones allow highly lipophilic compounds to be incorporated into a suitable colloidal delivery system before they can be dispersed into an aqueous-based system.
Technical Abstract: Cinnamaldehyde was delivered in emulsion form using Acetem 90-50K as a carrier and Tween 60 as emulsifier. Cinnamaldehyde interacted with Acetem 90-50K by forming H-bonds. The effect of disperse phase characteristics on storage stability, physical and antimicrobial properties was investigated. Storage test of emulsions was carried out for 15 days at two temperatures (22 and 4°C). Emulsions and nano-emulsions showed higher stability at 22 °C than at 4°C. Nano-emulsions displayed excellent stability vs. creaming and coalescence after 15 days storage at 22 °C (z-avg<100nm). Physical properties were greatly affected by droplet size and concentration. Emulsions became less viscous, more transparent and darker as the droplet size or concentration decreased. The antimicrobial activity was measured against Listeria monocytogenes and Escherichia coli. Escherichia coli was highly resistant to cinnamaldehyde compared to L. monocytogenes. Incubation with cinnamaldehyde at 2.5 mM caused the complete inactivation of L. monocytogenes after 1 day and of E. coli after 9 days. There was no difference in the antimicrobial effect of cinnamaldehyde due to different droplet sizes (~80 nm and ~5000 nm).