Encapsulation of plum biowaste extract: design of alginate beads by response surface approach

Abstract

The aim of this study is to recommend a preserving method of a natural plant extract for further food applications. Plum peel extract was used as active material source, and extracted by automatic solvent extraction. Ionic gelation was used to encapsulate the plum peel extract in alginate beads. The process was subjected to Box-Behnken design of response surface method (Box-Behnken-RSM). The conditions of CaCl2 concentration, sodium alginate concentration and hardening time for the ionic gelation system was optimized to obtain the best responses (encapsulation efficiency and antioxidant activity). 15% CaCl2, 1.44% alginate and 18 min were the best conditions for the highest encapsulation efficiency (EE) in terms of total phenolic content (TPC) and antioxidant activity of the capsules. In vitro DPPH (2,2-diphenyl-1-picrylhydrazyl) assay was applied in order to measure the antioxidant activity of the beads. Furthermore, stereo-microscope and scanning electron microscopy (SEM) were also used to analyze the morphology of the alginate beads. When the morphology of the obtained capsules was examined, it was observed that they were perfect sphere. However, it was determined that the samples were slightly far from perfect sphericity in the shape analysis.