Submitted to: Micron
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2010
Publication Date: 10/26/2010
Citation: Bilbao-Sainz, C., Wood, D.F., Williams, T.G., Mchugh, T.H., Avena Bustillos, R.D. 2010. Nanoemulsions prepared by a low-energy emulsification method applied to edible films. Micron. 58(22):11932-11938.
Interpretive Summary: Nanoemulsions have droplet sizes ranging between 50 and 500 nm. Nanoemulsions may have improved dispersions of oil in water and increased nutritional bioavailability. In addition, nanoemulsions have increased stablity and transparency depending on the components and method of preparation compared to microemulsions. Catastrophic phase inversion was used as a low-energy emulsification method to prepare oil-in-water nanoemulsions in a lipid /water/ surfactant system. Dynamic phase inversion emulsification was achieved by slowly increasing the water volume fraction to obtain oil in water emulsions from water in oil emulsions. The resulting composite films made from the nanoemulsions were composed of a continuous soy protein matrix with oil globules containing oregano oil had better mechanical and water vapor properties than the conventional films.
Technical Abstract: Catastrophic phase inversion (CPI) was used as a low-energy emulsification method to prepare oil-in-water (O/W) nanoemulsions in a lipid (Acetem)/water/nonionic surfactant (Tween 60) system. CPIs in which water-in-oil emulsions (W/O) are transformed into oil-in-water emulsions (O/W) were induced by changes in the phase ratio. Dynamic phase inversion emulsification was achieved by slowly increasing the water volume fraction (fw) to obtain O/W emulsions from water in oil emulsions. Composition and processing variables were optimized to minimize droplet size and polydispersity index (PdI). It was found that addition of the continuous phase to the dispersed phase following the standard CPI procedure resulted in the formation of oil droplets with diameters of 100-200 nm. Droplet size distribution during CPI and emulsification time depended on stirring speed and surfactant concentration. Droplet sizes in the inverted emulsions were compared to those obtained by direct emulsification: The process time to reach droplet sizes of around 100 nm was reduced by 12 times by using CPI emulsification. The Acetem/water nanoemulsion was also used as a carrier to incorporate oregano and cinnamon essential oils into soy protein edible films. The resulting composite films containing oregano oil showed better moisture barrier and mechanical properties compared to soy protein films.