Use of gelatin and gum Arabic for encapsulation of black raspberry anthocyanins by complex coacervation

Protein-polysaccharide interactions offer opportunities for designing the new functional foods with applications in the food and pharmaceutical industries. In this work, we microencapsulated black raspberry water extracts by double emulsion technique prior to complex coacervation using gelatin and gum Arabic to diminish the instability of their anthocyanins (ANCs) as water soluble compounds, particularly under harsh processing and storage conditions. Subsequently, optical microscopy, moisture, hygroscopicity, solubility, particle size, loading capacity, zeta potential, color parameters (L*, a*, b*, C, H° and TCD), stability, Fourier transform infrared spectroscopy (FTIR), and thermal behavior were evaluated. The microcapsules presented the lower moisture, hygroscopicity and solubility values as comparing the free form of ANCs. They showed the average sizes ranging from 35.34±3.21 to 80.22±5.21μm and high loading capacity (29.67±0.66-38.54±0.08%). According to the HPLC results, the selected method significantly increased the stability of ANCs up to 23.66% after 2 months of storage at 37±2°C. FT-IR spectra confirmed the negative zeta potential values of microcapsules and the occurrence of coacervation process. DSC results evidenced the thermostability of microcapsules. Furthermore, the selected optimal microcapsules revealed intense red color over the time of storage, implying the effectiveness of the method chosen to preserve anthocyanins.