15C-17 |
Effect of chelating agents and non-adsorbed whey proteins on physicochemical properties and stability of whey protein stabilized emulsions containing calcium. |
E. KEOWMANEECHAI and D. J. McClements. Department of Food Science, University of Massachusetts, Chenoweth Bd., UMASS, Amherst, MA 01003 A great number of nutritional beverages such as meal replacement drinks, athletic supplement drinks, and infant formula are protein stabilized emulsions. They are usually fortified with high contents of minerals that can interact with other ingredients and cause physicochemical instability reducing product shelf life. Our objective was to investigate the feasibility of using chelating agents and non-adsorbed whey proteins to improve stability of whey protein stabilized emulsions containing calcium, a major mineral fortified in nutritional beverages. EDTA (0-40 mM), citrate (0-40 mM), whey protein isolate (0-5 %), and calcium chloride (0-15 mM) were added into oil-in-water whey protein stabilized emulsions (7 % soy oil, 0.35 % whey protein isolate, 0.02 % sodium azide, 20 mM Tris buffer, pH 7.0). Then, particle size distribution, droplet surface charge (as zeta potential), free calcium concentration, rheological properties, and creaming stability of the emulsions were measured. The results showed that adding EDTA or citrate at molar ratio (chelating agent/ calcium chloride) 0.35 or higher decreased particle size and viscosity, and increased droplet surface charge and creaming stability. Adding 1.25 % whey protein isolate or higher decreased particle size, viscosity and free calcium concentration, and increased creaming stability. The ability of EDTA, citrate, and non-adsorbed whey proteins to increase emulsion stability was due to their ability to bind calcium, thereby decreasing free calcium ions that can cause emulsion instability by electrostatic screening and droplet surface charge reduction. This suggested that using EDTA, citrate, and non-adsorbed whey proteins have a potential for extending shelf life of nutritional beverages.
Session 15C, Dairy Foods
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