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Lignin nanoparticles (LNPs) from lignocellulosic biomass are expected to become promising basic building blocks for various applications in the development of multifunctional nanocomposites. Facile green preparation of LNPs and their application in polyvinyl alcohol (PVA) composite films were studied in this paper. LNPs were produced by performing fractionation of wheat straws at less than 80 °C with a recyclable hydrotropic, aqueous p-toluene sulfonic acid (p-TsOH). The dissolved lignin could be simply separated as LNPs by diluting the spent liquor (SL) to below the minimal hydrotropic concentration (MHC) of 11.5%. The resulting LPNs exhibited an oblate spheroid morphology and a uniform particle size distribution. After introducing the available LNPs into the PVA matrix at 6% loading, the nanocomposite products could block 100 and 95% of UV light at 315 and 400 nm, respectively, and exhibited 80% antioxidant activity. In addition, the respective maximum TS and TM were 59.7 MPa and 2.07 GPa, respectively, which were increases of approximately 36 and 104% compared with those of pure PVA film. The LNPs/PVA nanocomposite films displayed improved UV resistance, mechanical properties, thermal stability and antioxidant activity and could be used as additional multifunctional agents in the fields of biodegradable plastics, tissue engineering and UV-protective biobased materials.

High‐load flaxseed oil microcapsule is prepared with the Maillard reaction products (MRPs) of sodium caseinate and isomaltooligosaccharide as wall material. It is found that the emulsifying activity index and emulsion stability index of MRPs are increased by 31.32% and 34.11% respectively at the appropriate degree of graft (26.30%) compared with the mixture of sodium caseinate and isomaltooligosaccharide. Smaller droplet size and lower polydispersity index can be achieved in the flaxseed oil emulsions coated by MRPs, due to the change of sodium caseinate molecular weight and spatial structure. The microencapsulation efficiency of the microcapsules coated by MRPs is highly improved up to 98.22% at oil load of 58.43%, compared with the control group. Furthermore, MRPs as coating material can protect flaxseed oil against lipid oxidation at 50 °C for 4 weeks. More importantly, the smooth, round, and compact external surface structures of microcapsule powder support its physical necessity for industrial usage. Due to its high microencapsulation efficiency and good oxidation stability, MRPs formed with sodium caseinate and isomaltooligosaccharide show great application potential in preparing high load oil microcapsule. Practical Applications: Findings in this research could be utilized for developing microencapsulation loaded with higher concentration of flaxseed oil, a rich source of α‐linoleic acid and lignans. Application of MRPs (Maillard reaction products) formed through interaction between sodium caseinate and isomaltooligosaccharide by heating improved both its physicochemical properties and oxidative stability. It is a novel approach for developing microcapsule with higher percentages of oils with better oxidative stability.