Cold gelation creates applications for gels.

Whey protein emulsion gels can help us create foods that have new and improved organoleptic properties. However, the thermal treatment needed to produce these gels prevents their application in formulations that contain heat-sensitive ingredients. An alternate gelation technique, involving calcium and low temperatures, i.e., cold gelation, could be harnessed to overcome this limitation.

The goal of Canadian scientists was to develop cold-set [beta]-lactoglobulin (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 wt% to 30 wt%) with a solution of pre-denatured [beta]-lg (6.5 wt% protein). To induce cold gelation, researchers mixed the emulsions with different concentrations of calcium (12 mM to 68 mM). The emulsion gels that were produced were characterized using dynamic small strain rheometry and electron microscopy techniques. The water-holding capacity of these gels was also determined by centrifugation.

The scientists found that higher oil concentrations improved the elasticity and the ability of emulsion gels to physically hold water. In fact, raising the oil content in the emulsion led to a greater number of oil globules in the gel matrix, which served as many anchor points that strengthened the three-dimensional network.

In contrast, increasing calcium levels caused the structure of the emulsion gels to change from a filamentous to a particulate structure. This decreased the water retention capacity without affecting the gel rheological properties. Oil and calcium regulated how the gel network formed and modulated the functional properties of cold-set emulsion gels. A balance between the antagonistic effects led to emulsion gels with unique properties that can be tailored to specific applications.

Further information. Muriel Subirade, Stela Dairy Research Centre, Nutraceuticals and Functional Foods Institute, Laval University, Faculty of Agricultural and Food Sciences, Paul- Comtois Building, Room 1415, Quebec, QC, G1K 7P4 Canada; phone: [phone]; fax: [phone]; email: [e-mail].