Oil in Water in Water (O/W/W) Emulsions As Food Dressings with a Low Content in Oil

Food products such as dressings are generally emulsions, and as texture of emulsions depends on the volume fraction of the disperse phase, these products frequently have a high content of oils. For this reason, food industry tries to obtain products with less fat content but with an acceptable texture. The objective of this work is to obtain oil in water in water emulsions (O/W/W) with a low oil content, but presenting rheological behavior similar to dressings with much more oil content. Oil in water emulsions have been prepared by emulsifying sunflower oil in aqueous solutions of casein. Influence of composition and preparation variables was studied for having adequate droplet size and stability. O/W emulsions obtained have drop size around 3 microns, and are stables for more than 30 hours.

O/W emulsions were dispersed in alginate aqueous solutions, obtaining a multiple emulsion of oil in water in water (O/W/W). Influence of composition and preparation variables was studied, and O/W/W emulsions obtained have drop size about 15-25 microns, are stables for more than 10 hours, and contain such a lower concentration in oil as 5%.

Subsequently, the multiple emulsion has been gelled with calcium ion at different concentrations and rheological behavior of final emulsions was determined. Emulsion gelation starts at a minimum global concentration of calcium of 7 mM and at 8 mM emulsion is gelled. Over time, emulsion becomes more gelled. A rise in calcium concentration increases slightly viscosity values, with a shear thinning behavior. Elastic modulus is higher than loss modulus.

The rheological behavior of multiple emulsions obtained is similar to commercial dressings, mimicking mayonnaise, for example, but with much less oil content.

AcknowledgementsThe authors wish to thank the Spanish Ministry of Economy and Competitiveness for financial support through project CTQ2016-80645-R, and the FEDER funds of the European Union