Optimization of purple sweet potato anthocyanins microcapsules by response surface methodology

Objective: The wall materials for the microcapsulation of purple sweet potato anthocyanins were selected to improve their stabilization in aqueous phase and the response surface was used to optimize the process conditions.Methods: The selected parameters including microcapsulation tempreture, time, wall material concentration, wall/core material ratio were optimized using Box-Behnken experimental design with variance analysis based on the microcapulation efficiency. The prepared microcapsules were subjected to electron microscopic observation and stability test.Results: The zein was selected as the wall material.The results showed that the optimal microcapsulation results were obtained under the conditions: microcapsulation time30 min, tempreture 31 ℃, wall material concentration 1%, wall/core material ratio 5 ∶ 2.2 ( w/w) . Under these optimal conditions, the microcapulation efficiency was up to 81.55% ± 0.89%, their density was 2.88 g/m L, moisture content was4.42%.The anthocyanins microcapsules were purple with a cylinder-like shape. The microcapsules were more stable than the native anthocyanins when exposed to aqueous phase, p H and outdoor light.Conclusion: Therefore, microcapsulation is a good way to improve the stabilization of purple sweet potato anthocyanins in aqueous phase.