The effect of an ultrasonic spray nozzle on carbohydrate and protein-based coating materials for blueberry extract...

An ultrasonic spray nozzle was evaluated for the production of powders and microcapsules, using blueberry extract, modified starch (HI-CAP 100), and whey protein isolate (WPI). The effects of ultrasonic power and the concentration of coating materials on the characteristics of the resulting samples - such as viscosity, particle size, microencapsulation efficiency, color, glass transition temperature, Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and morphology - were also studied.

The apparent viscosity was primarily affected by the self-heating of the ultrasonic nozzle as the power increased. The largest mean particle size of samples was observed under conditions of 30% coating concentration at 10 W. Glass transition temperatures (T_g ) of the samples were affected by all atomization parameters significantly (P < 0.05) and the highest T_g values of all samples were determined when the coating concentration was maximum (30%) and power level was minimum (5 W). The FTIR and XRD results indicate that the power of the ultrasonic nozzle did not cause any change in WPI structure and led to only a small change in the structure of HI-CAP 100 at 10 W. The short atomization time preserved, to some extent, the properties of the coating materials and the blueberry extract. With regard to the morphological properties, it was observed that the samples obtained with WPI showed less shrinkage than HI-CAP 100.

The results indicated that an ultrasonic nozzle could be used successfully to prepare the blueberry microcapsule with HI-CAP 100 and WPI as coating materials. This study may contribute to the development of ultrasonic nozzle applications using different coatings for the microencapsulation of high-quality functional materials. © 2020 Society of Chemical Industry.