Development of microencapsulated anthocyanin-rich powder using soy protein isolate, jackfruit seed starch and an emulsifier (NBRE-15) as encapsulating materials

A trend of present encapsulation research indicates an increased interest in the search for natural encapsulants for bioactive phytochemicals. The present study in pursuit of the same studies the use of jackfruit seed starch (JSS), an underutilized natural polysaccharide in conjugation with soy protein isolate (SPI) as an encapsulating material and NBRE-15 as an emulsifier. Three independent variables viz., total soluble solids (TSS, 20, 25 and 30° Brix), SPI: JSS (1:1, 1:3 and 1:5) and NBRE-15 (0.1, 0.2 and 0.3%) were optimized for achieving the most efficient encapsulation of anthocyanin using a three level, three parameter, Box-Behnken design (BBD) of the Design of Experiments (DOE). The responses considered for the optimization were monomeric anthocyanin content, antioxidant activity and encapsulation efficiency. A combination of 27.0% TSS, 1:5 SPI: JSS ratio and 0.3% NBRE-15 was found to be optimum for the encapsulation of anthocyanin with the desirability of 92.6%. Microcapsules obtained using the optimized combination of independent variables was found to contain 3215.59 mg/100 g monomeric anthocyanin. The antioxidant activity and encapsulation efficiency of the encapsulated material obtained using optimized combinations of independent variable were found to be 365.26 µmol Trolox/g and 89.71%, respectively. The microcapsules were also additionally analyzed for the particle size distribution and morphological characterization. Particle size analysis indicated that the microcapsules obtained had a mean particle size of 60.97 µm. Scanning electron microscopy for morphological characterization indicated that the microcapsules so obtained were oval to round in shape and had a smooth surface. Storage studies to estimate the half-life of anthocyanin in the microcapsule at room temperature (37 °C) clearly indicated greater stability i.e. 63 days when stored under amber-colored vial compared to only 35 days when stored under clear transparent vial.