INFLUENCE ON STABILITY AND PARTICLE SIZE FROM DIFFERENT SYSTEMS OF PECTIN-BASED EMULSION WITH STARCH ADDITION

Emulsion is a heterogeneous system composed of a dispersed phase and a continuous one. The addition of stabilizers as polysaccharides allows forming a more stable mixture. Pectin is one of the soluble fibers most used by food industry as a gelling agent, thickener and stabilizer. Starches exhibit stability, versatility, can form a consistent gel and it is well incorporated into foods that require high viscosity. The combination of starch and pectin (both GRAS and low cost) to develop emulsion is promising, since the interaction between these two biopolymers can contribute to a more viscous system with better stabilizing potential than the use of only one compound. The arrangement of the compounds may influence the way the emulsions are formed and/or stabilized. Therefore, the objective of this study was to investigate emulsion stability and particle size of two systems consisted of sunflower oil, protein (whey protein isolate - WPI) and polysaccharides (starch and pectin) under ultrasound treatment. For the first system, named as active emulsions, the oil was emulsified on the biopolymeric solution containing WPI and for the second one (inactive), a previous emulsion was prepared solely with WPI prior its mixture with the starch-pectin solution. The order of adding WPI influenced the particle size diameter of each emulsion. After 7 days of storage, results showed that Sauter mean diameter was larger to inactive emulsions while smaller sizes were observed for active emulsions, indicating that oil droplets from the active emulsions may have coalesced. Immediately after preparation, both systems presented stability against creaming and phase separation. Even though a greater interaction among the compounds was expected for the active emulsions, the inactive emulsions were stable for longer which was associated to the WPI coating the entire surface of the oil droplets, which protected them against aggregation. This study indicated that even adding the same components, the procedure can influence the particle size as well as the stability of an emulsion. The results showed that a biopolymer stabilized emulsion containing a pre-emulsion provides better performance against phase separation.