Caracterización reológica y estructural de complejos coacervados de proteína de amaranto-pectina cítrica

Abstract

Complex coacervates were formed by electrostatic interaction between amaranth protein isolated (API) and citrus pectin (CP), at different API:CP weight ratio (3:1, 5:1, and 7: 1) and pH values (3.5 and 4.5). The physicochemical, rheological, and microstructural properties of the coacervates were investigated. The FTIR spectrum of the coacervates showed changes in the peaks at 1636 and 1153 cm-1 compared to the spectrum of API and CP, confirming the formation of the complex coacervates. A fine, structured, and compact structure was observed in the coacervates formed at pH 3.5; in contrast, a matrix composed of relatively large aggregates was observed for the coacervates formed at pH 4.5. Particle size of the coacervates increased as the API:CP weight ratio and pH increased, ranging the hydrodynamic diameter (Dh) from 1043 ± 39 to 2670 ± 30 nm. The apparent viscosity of the coacervates increased as the API:CP weight ratio increased and pH decreased. All the variations of complex coacervates presented G' values (storage modulus) higher than the G'' values (loss modulus), indicating a predominantly elastic rheological behavior. The knowledge generated could contribute to the application of the studied complex coacervates in the food industry.