17E-27 |
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V. LEUNG SOK LINE1, G. E. Remondetto, and M. Subirade. (1) STELA Dairy Research Centre, Nutraceuticals & Functional Foods Institute, Laval Univ., Canada Research Chair in Proteins, Biosystems & Functional Foods, Faculty of Agricultural & Food Sciences, Paul-Comtois Bldg., Quebec, QC G1K 7P4, Canada The use of whey protein emulsion gels extends the possibilities for creating foods with new and improved organoleptic properties. However, the thermal treatment needed to produce these emulsion gels prevents their application in formulations containing heat-sensitive ingredients. An alternate gelation method, involving calcium and low temperatures (i.e., cold gelation), could be judiciously exploited to overcome this limitation. Our objective was to develop cold-set b-lactoglobulin (b-lg) emulsion gels and study the effects of oil and calcium concentrations on their rheological and structural properties. Oil-in-water emulsions were prepared by homogenizing various amounts of sunflower oil (10 to 30 wt%) with a solution of pre-denatured b-lg (6.5 wt% protein). To induce cold gelation, emulsions were then mixed with different concentrations of calcium (12 to 68 mM). The obtained emulsion gels were further characterized using dynamic small strain rheometry and electron microscopy techniques. The water-holding capacity of these gels was also determined by centrifugation method. Results showed that higher oil concentration improved the elasticity and the ability of emulsion gels to physically hold water. In fact, raising oil content in the emulsion led to a greater number of oil globules fitted into the gel matrix, which served as many anchor points that strengthened the three-dimensional network. In contrast, increasing calcium levels caused the structure of emulsion gels to change from filamentous to particulate type and decreased the water retention capacity without affecting the gel rheological properties. Oil and calcium regulated the process of gel network formation and modulated the functional properties of cold-set emulsion gels. The balance between their antagonistic effects resulted in emulsion gels of unique properties that can be tailored to specific food applications.
Session 17E, Food Chemistry: Proteins
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