Valorization of plum (Prunus domestica) peels: microwave-assisted extraction, encapsulation and storage stability of its phenolic extract

The objective of this study is to optimize a new extraction method of plum peels phenolics and its application in food industries, based on the microwave-assisted extraction (MAE) of phenolic compounds followed by their encapsulation by spray drying. Maltodextrin percentage in the coating material (30–70%), coating to core ratio (2:1–4:1) and air inlet temperature (130–190 °C) were selected as the independent variables according to a Box Behnken design, and their effects on response variables (encapsulation yield, encapsulation efficiency and moisture content) were evaluated. Optimum conditions were a maltodextrin percentage of 60%, a coating to core ratio of 4:1 and an inlet temperature of 190 °C. Under these conditions, the experimental response variables were an encapsulation efficiency of 94.64%, an encapsulation yield of 76.97% and a moisture content of 1.29% and were in strong agreement with predicted values. Detailed physicochemical analyses revealed that the optimum microcapsules had the high solubility and encapsulation efficiency, acceptable electrical and thermal stability and good morphological structure. Microcapsules color and antioxidant capacity were preserved during storage. These findings suggest the effectiveness of the optimized spray drying process for producing high quality microcapsules and the possibility of their use in functional foods or pharmaceutical products.