Microencapsulation of sweet orange oil by complex coacervation with soybean protein isolate/gum Arabic

The coacervation between soybean protein isolate (SPI) and gum Arabic (GA) for sweet orange oil microencapsulation as functions of pH, ionic strength, SPI/GA ratio, core material load and micromolecules was investigated. SPI was exposed to ultrasonic to increase solubility before use and microcapsules were spray-dried before analysis. It was found that the optimum pH for SPI/GA coacervation was 4.0. High ionic strength reduced the coacervation between the two biopolymers. The highest coacervate yield was achieved in SPI/GA ratio 1:1 and the core material load for the highest microencapsulation efficiency (MEE) and microencapsulation yield (MEY) was 10%. The addition of sucrose in sucrose/SPI ratio 1:1 increased the MEY by 20%, reaching 78% compared to 65% of control. The microcapsules were spherical without holes on the surface by SEM observation and flavour components were well retained in microcapsules according to GC–MS analysis, indicating good protection for core material.