The stability of the biopolymer particles across a pH range may make them ideal substitute for lipid droplets in foods, or to encapsulate value-added bioactive ingredients, according to research published in Food Hydrocolloids.
“These biopolymer particles could be used as fat mimetics (e.g., to simulate the light scattering or viscosity of fat droplet suspensions) or they could be used as delivery systems (e.g., to encapsulate bioactive components),” wrote the researchers, led by D. Julian McClements from the Department of Food Science at the University of Massachusetts.
Reduction of fat in products is a growing area of interest to food manufacturers as consumers continue to seek out low-fat and low-calorie versions of their favourite foods.
The work builds on an earlier report from the McClements’ group, published in the Journal of Food Science, which described the electrostatic deposition process to prepare so-called coreshell biopolymer particles.
Dr McClements told FoodNavigator in July 2008 that the particles may be useful for a number of reasons: Opacity - mimicking light scattering by fat droplets to make cloudy systems, which could be applied to beverages, and texture modification - viscosity and mouthfeel modification delivery systems - encapsulation, protection and delivery of functional components.
The new study combined the electrostatic process with a thermal treatment to promote the unfolding of the protein and then cross-linking between beta-lactogloblin (Davisco Foods) and sugar beet pectin (Herbstreith & Fox KG).
“We hypothesize that heat-treated complexes will have different physicochemical properties than untreated complexes,” wrote the researchers. “In particular, we postulate that they will be more stable to changes in environmental conditions, such as pH, than untreated complexes because of the increased attraction between the thermally denatured globular proteins.”
Combining the processes produced relatively small biopolymer particles with an average diameter of 300 nanometres.
Tests in acid and alkaline conditions revealed the particles were stable “over a relatively wide range of pH values, which depends on polysaccharide concentration”, they said. “At sufficiently high polysaccharide concentrations, biopolymer particles could be formed that remained intact from pH 3 to 7, which covers most of the range important for food applications,” added Dr McClements and his co-workers.
The researchers noted that additional work is needed to better understand the events that occur during formation of the protein-polysaccharide electrostatic complex.
Source: Food Hydrocolloids
July 2009, Volume 23, Issue 5, Pages 1312-1321
"Formation of biopolymer particles by thermal treatment of beta-lactoglobulin-pectin complexes"
Authors: O.G. Jones, E.A. Decker, D.J. McClements