The study, published in the journal Food Hydrocolloids, reports an improved approach for the optimal production of transparent, food grade nano-emulsions, using high energy microfluidization.
“There is strong interest in the food and other industries in the use of nano-emulsions as delivery systems for non-polar functional components, such as lipophilic bioactive lipids, drugs, flavours, antioxidants, and antimicrobial agents,” wrote the researchers from the Department of Food Science at the University of Massachusetts.
“Emulsions that do not scatter light strongly can be produced by homogenizing a relatively low viscosity oil phase with a relatively high viscosity aqueous phase,
“In the food industry, flavour oils or essential oils could be used as low viscosity oils, rather than hydrocarbons,” they added.
Nano-emulsions being increasing used in the food and beverage industries because of their valuable properties, including high encapsulation efficiency, increased bioavailability, and a high physical stability.
The authors noted that one major potential advantage of nano-emulsions over conventional emulsions “is that they can be made to be optically transparent, by preparing droplets with dimensions much smaller than the wavelength of light… so that [light] scattering is relatively weak.
“Consequently, they can be used to incorporate non-polar functional components into transparent … food and beverage products,” they added
Nano-emulsions generally have much better stability to gravitational separation than conventional emulsions, and also tend to have better stability against droplet growth, which could lead to transparent emulsions becoming opaque.
Previous research has suggested the bioavailability of encapsulated components is higher in nano-emulsions than conventional emulsions, because the small particle size gives a higher surface-to-volume ratio.
Studies have shown that the minimum particle size achievable using a high energy approach depends on many different factors, including homogenizer type, operating conditions, and the sample composition.
Using the high energy approach of microfluidisation, the Massachusetts-based scientists produced transparent nano-emulsions where the choice of the co-solvent and surfactants were found to affect particle size.
Adding a co-solvent like glycerol could reduce the final droplet sizes, while small molecule surfactants performed better than biopolymers like beta-lactoglobulin or caseinate, said the researchers.
They concluded that their research “has important implications for optimizing the composition and homogenization conditions required to produce food-grade nano-emulsions.”
Source: Food Hydrocolloids
Published online ahead of print, doi: 10.1016/j.foodhyd.2010.09.017
“Formation of Nanoemulsions stabilized by Model Food-Grade Emulsifiers using High Pressure Homogenization: Factors Affecting Particle Size”
Authors: C. Qian, D.J. McClements