Effect of sodium caseinate concentration and sonication amplitude on the stability and physical characteristics of homogenized coconut milk

The ultrasonic homogenization of coconut milk with added sodium caseinate (SC) was carried out to reduce the fat globules size and stabilize the emulsion. The coconut milk was mixed with SC at different concentrations from 0.5% to 2% w/w. The sonication was conducted at different sonication amplitudes (60%, 80% and 100%). The primary and effective droplet size, viscosity, homogenization efficiency and free fat content of the homogenized emulsion were characterized. Ultrasonic homogenization significantly reduced the average particle size to lower than half of its original size and reached to sub‐micron range size. Increasing the SC concentration positively reduced both the creaming index and free fat content without significant change in apparent viscosity. In this study, the changes in the physical characteristics of the emulsion were more affected by the SC concentration than the amplitude setting percentage. Nevertheless, both parameters were important in the formation of submicron‐sized droplets. PRACTICAL APPLICATIONS: Coconut milk is highly unstable and vulnerable to oxidation. Due to its low stability, it can easily separate into two phases. Instability of the emulsion leads to the instability of the spray‐dried product. The homogenization of coconut milk fat with emulsifiers is widely conducted to increase the emulsion stability. The homogenization process will reduce the fat globules size while the emulsifier will lower the interfacial tension between the oil and water phases. However, sufficient power and amount of emulsifier are required in order to achieve high stability of the emulsion. The effects of the sonication amplitude and SC concentration on the stability of the coconut milk were investigated. The detailed knowledge obtained from this study on the optimum sonication amplitude and SC concentration can be utilized to improve the emulsion stability while taking food safety into consideration. Additionally, the physical characteristics of the emulsion are also determined, and results are found to be promising for the production of high stability emulsions.