Design emulsion-based delivery systems.
Emulsion-based delivery systems are needed to encapsulate, protect and deliver lipophilic bioactive components in foods and other products. These delivery systems must be edible. So, this places constraints on the type of ingredients and processing operations that can be used to create them.
Emulsion technology is particularly suited for the design and fabrication of delivery systems for encapsulating bioactive lipids. The functional performance of these systems can be controlled by engineering the composition and structure of the interfacial layer coating the lipid droplets.
Scientists at the University of Massachusetts controlled interfacial properties using two globular proteins with widely differing isoelectric points: lactoferrin (pI [approximately equal to] 8.5) and beta-lactoglobulin (pI [approximately equal to] 5). Their work generated useful information for designing emulsion-based delivery systems to encapsulate and protect bioactive lipids, such as carotenoids.
Oil-in-water emulsions were prepared with different interfacial properties: lactoferrin only, beta-lactoglobulin only; lactoferrin and beta-lactoglobulin; beta-lactoglobulin and lactoferrin; and mixed beta-lactoglobulin and lactoferrin. The researchers examined the influence of pH, ionic strength and temperature on the physical stability of beta-carotene-enriched emulsions. They found that lactoferrin emulsions were stable to droplet aggregation from pH 2 to 9, but all other emulsions aggregated at intermediate pH values. Beta-lactoglobulin emulsions aggregated at high salt levels--equal to or greater than 50 mM NaCl. But all other emulsions were stable.
Beta-lactoglobulin-lactoferrin emulsions were unstable to heat at equal to or greater than 60 C. But all other emulsions were stable at from 30 C to 90 C. Color fading caused by the degradation of beta-carotene occurred relatively quickly in beta-lactoglobulin emulsions at 37 C, but was considerably lower in all other emulsions. Fading color was attributed by the scientists to the ability of lactoferrin to bind iron or interact with beta-carotene.
Further information. D. Julian McClements, Department of Food Science, University of Massachusetts Amherst, Room 250, Chenoweth Laboratory, Amherst, MA 01003; phone: 413-545-1019; email: email@example.com.