Gelatin and pectin complex coacervates as carriers for cinnamaldehyde: Effect of pectin esterification degree on coacervate formation, and enhanced thermal stability

This study developed the multinuclear microcapsules by the complex coacervation between gelatin (G) and high methyl pectin (HMP), low methyl pectin (LMP) as a delivery system for cinnamaldehyde. The parameters affecting the formation of such carriers were investigated by dynamic light scattering and microscopic techniques. Fluorescence analysis and Fourier-transform infrared (FTIR) were used to study protein conformation change during coacervate formation between gelatin and pectin. The results showed that high yield of coacervates with good size and morphology occurred at pH 4.23 and 4.37 for G/HMP with a ratio of 3:1 and G/LMP with a ratio of 6:1 respectively. Fluorescence and FTIR analysis further confirmed their electrostatic interaction and gelatin molecules exhibited a conformational change following the complexation. Thermal gravimetric analysis revealed that microencapsulation of cinnamaldehyde by complex coacervation using gelatin and pectin significantly increased the degradation temperature from 180-220 °C to 350–400 °C. Moreover, high methyl pectin revealed a higher encapsulation efficiency (89.2%) and controlled release of cinnamaldehyde in hot water (33% for 120 min at 80 °C). It could be suggested conformation of pectin types and gelatin might significantly contribute to the overall complexation and cinnamaldehyde microcapsule properties. These findings could be useful for design an ideal carrier to deliver flavors like cinnamaldehyde by complex coacervation using protein and different pectin types.