In this study, a series of emulsion gels were prepared by dispersing emulsified oil droplets into alginate (Alg) gel matrix, and the final emulsion gels contained 2% Alg (w/v), 0.5% Tween 80 (v/v) and gradient concentrations of oil phase fractions (5-30%, v/v). Subsequently, the effects of Ca2+ addition, heating, and freeze thawing treatments on the emulsion gels were also investigated by a combination of rheological tests, confocal and scanning electron microscopy techniques. It was found that within the range of 0-30% of oil phase fraction, 0-0.15% of CaCl2 addition (w/v), all the emulsion gels could achieve significant thixotropy and good emulsion stability, without discernible oil droplet coalescence observed after heating and/or freeze thawing treatments. The yield stress value and gel stiffness increased with increasing oil phase fraction and Ca2+ addition, which is attributed to the strengthened gel network cross-links in the emulsion gels, as confirmed by SEM results. Interestingly, after freeze thawing treatment, the gel stiffness was slightly improved, which may be due to the intermolecular self-association of Alg during freezing stage. Overall, these results show the potential application of Alg-stabilized emulsion gels in preparation of low-fat mayonnaise products and other similar emulsion foods.
Keywords: Alginate; Emulsion gels; Mayonnaise; Rheological properties.
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