In this study, Chitosan (CS) was newly found as an effective carrier for micro-encapsulation of Pg by spray drying technique for enhancing its bioactivity. Among various tested polymers, CS was screened as the most suitable substance for creating encapsulated Pg/CS microparticles (E-Pg/CS-MPs) with high recovery yield and good nanoscale properties. CS was further combined with other carbohydrate polymers and used for micro-encapsulation of Pg, however, no enhancing yield or better properties of encapsulated Pg microparticles were found. Further experiments indicated that the size of the spaying needle of 5.5 μm and the Pg concentration used at 0.05% were the most effective for producing E-Pg/CS-MPs. In nanoscale properties characterization, the E-Pg/CS-MPs were found spherical with smooth surfaces, good stability (Zeta potential of + 80.1 mV), and average sizes at 529.5 nm. Especially, the E-Pg/CS-MPs demonstrated a potent nematicidal effect against both J2-nematodes and their egg-hatching, besides, the activity of E-Pg/CS-MPs was improved by about fourfold compared with pure Pg. The molecular docking and enzyme inhibition assays suggested the possible pathway of the nematicidal effect of Pg released from E-Pg/CS-MPs via inhibition of acetylcholinesterase. This study thus provides a novel and effective protocol to produce E-Pg/CS-MPs with potential use for managing black pepper nematodes.
