In-pack sonication technique for edible emulsions: Understanding the impact of acacia gum and lecithin emulsifiers and ultrasound homogenization on salad dressing emulsions stability

The potential of ultrasound as a complementary technique for enhancing the stability of in-packed food emulsions, such as mayonnaise, without changing the conventional packaging material was evaluated. For this purpose, model salad dressing emulsions containing acacia gum and lecithin were stabilized by ultrasound within the package and their physical stability, particle size distribution, color, and consistency were compared to those stabilized by conventional power ultrasound and mechanical homogenization. Although both emulsifiers improved the stability of the emulsions, the stability of lecithin-containing samples was up to 5.4 times higher than the AG-containing counterparts. Turbiscan and laser particle size analysis showed that power sonicated sample containing lecithin had the highest physical stability (migration rate of 0.1 mm/h) with the smallest particle size (2.9 +/- 0.2 mu m). Conventional power ultrasound was superior compared to the other investigated techniques regarding saving energy, improving product's stability and appearance, and decreasing emulsifier demand. The in-pack sonication technique also stabilized oil-water mixtures in the presence of a capable natural emulsifier (migration rate of 30 mm/h) and saved up to 73% of emulsification energy as compared to the mechanical homogenization. The stability of the in-pack sonicated sample containing lecithin was comparable to that of the mechanically homogenized sample in the presence of acacia gum (migration rate of 30.4 and 32.9 mm/h, respectively). The proposed homogenization technique gave an emulsion with the smaller droplet size (31.7 +/- 0.2 mu m), enhanced the stability of the studied model salad dressing, and addressed the drawback of conventional power ultrasound technique by segregating the food product and ultrasound horn. (C) 2018 Elsevier Ltd. All rights reserved.