High solids emulsions produced by ultrasound as a function of energy density

The use of emulsifying methods is frequently required before spray drying food ingredients, where using high concentration of solids increases the drying process yield. In this work, we used ultrasound to obtain kinetically stable palm oil-in-water emulsions with 30 g solids/100 g of emulsion. Sodium caseinate, maltodextrin and dried glucose syrup were used as stabilizing agents. Sonication time of 3, 7 and 11 min were evaluated at power of 72, 105 and 148 W (which represents 50%, 75% and 100% of power amplitude in relation to the nominal power of the equipment). Energy density required for each assay was calculated. Emulsions were characterized for droplets mean diameter and size distribution, optical microscopy, confocal microscopy, ζ-potential, creaming index (CI) and rheological behavior. Emulsions presented bimodal size distribution, with D[3,2] ranging from 0.7 to 1.4 μm and CI between 5% and 12%, being these parameters inversely proportional to sonication time and power, but with a visual kinetically stabilization after the treatment at 148 W at 7 min sonication. D[3,2] showed to depend of energy density as a power function. Sonication presented as an effective method to be integrated to spray drying when emulsification is needed before the drying process.