Encapsulation of Ginger Essential Oil Using Complex Coacervation Method: Coacervate Formation, Rheological Property, and Physicochemical Characterization

Ginger essential oil (GO) was encapsulated with whey protein isolate (WPI)/gum Arabic (GA) and GA/chitosan (CH) complex coacervates. Best complex coacervate yields (43 and 73%) were obtained when using mass ratios of 3:1 (w:w), for WPI/GA, and of 5:1 (w/w) for GA/CH, respectively, and both behaved as shear thinning fluids. Frequency sweep revealed that G″ predominated over G′ for the both complex coacervate at low frequency values, and a crossover between the viscoelastic moduli occurred at about 5 Hz for GA/CH and at 60 Hz for WPI/GA. The magnitude of the viscoelastic moduli was higher for GA/CH than for WPI/GA. The creep-recovery tests showed that the coacervates with GO resulted in higher compliance values and weaker internal network structures. The Burgers model equation and exponential decay function were adequate to adjust the experimental data and describe the coacervate creep and recovery behavior, respectively. The obtained coacervates were freeze-dried for 48 h and then characterized concerning entrapment efficiency, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), solubility, and hygroscopicity. FTIR analyses revealed that only physical interactions occurred between the functional groups of GO and of WPI/GA and GA/CH complexes. TGA showed that wall materials contributed to a significant increase in the GO thermal stability and also evidenced some non-encapsulated GO present on the surface of WPI/GO/GA powders. The entrapment efficiency was 55.31 and 81.98% using complex of GA/CH and WPI/GA, respectively, revealing GA/CH as a more efficient complex for the GO protection (p < 0.05).