Flaxseed gum nano-microcapsules loaded with secoisolariciresinol diglucoside: Preparation and characterization

Flaxseed gum (FSG) has promising applications in the field of nano/microencapsulation for its biocompatibility and excellent physicochemical properties. In this study, FSG-based nano-microcapsules (FSG NPs) were prepared using high-speed shear homogenization combined with ultrasound for efficient encapsulation of secoisolariciresinol diglucoside (SDG). The particle size of FSG stands for nano-microcapsules (NP) was determined to be 336.96 nm, with a polydispersity index of 0.261. Adsorption kinetics, isotherms, antioxidant activity, surface morphology, rheological properties, and thermal stability were analyzed for FSG NP loaded with SDG. The results of adsorption kinetics analysis indicated that a pseudo-second-order kinetic model could effectively predict the adsorption behavior, with a predicted adsorption capacity of 9.140 mg g^-1. The Freundlich isotherm fit well with the isothermal model, indicating a non-uniform adsorption process of SDG. According to morphometric analysis, the surface of the nano-microcapsules was smooth without obvious breakage. SDG-loaded FSG NP exhibited low viscosity, high antioxidant activity, and good thermal stability. In vitro release results showed that FSG-SDG NP has a lower release rate in gastric fluid compared to intestinal fluid, which helps to achieve targeted release of SDG in the intestine. These findings provide a way to valorize FSG: As a hydrophilic food colloid, it can be used to produce microcapsules that can be loaded with bioactive compounds.