Formulation and characterization of microcapsules encapsulating carvacrol using complex coacervation crosslinked with tannic acid

Carvacrol-loaded microcapsules were developed based on coacervation complexes of whey protein isolate (WPI) and high methoxyl pectin (HMP), followed by cross-linking with tannic acid (TA). Optimal pH and WPI-HMP ratios for complex coacervation were found to be 4.1 and 5:1, respectively. Coacervation complexes were used to encapsulate carvacrol. Optimum conditions for achieving morphology and encapsulation efficiency were found for wall materials with a concentration of 2% (w/v), a wall/core ratio of 1:2 (w: w), and a homogenization speed of 15,000 rpm. The optimized formulation of microcapsules has an encapsulation efficiency of 77.48 ± 0.03% for carvacrol and a size of 1.08 μm. The addition of tannic acid (TA) decreased particle size and had no other influence on the morphological properties of microcapsules. Additionally, Fourier transform infrared spectroscopy (FTIR) indicated that coacervates were formed through the electrostatic interactions between WPI and HMP and the main force between TA and coacervates is hydrogen bonding. The addition of HMP to WPI and the presence of TA both decreased the content of tryptophan residues. Carvacrol microcapsules crosslinked with TA demonstrated better stability and antioxidant properties, showing potential for encapsulation of bioactive substances.