Natural Functional Polysaccharides and Their Application in Food Security

Natural functional polysaccharides are biodegradable, safe, and bioactive macromolecules that contribute significantly to food security. This review provides a systematic overview of their classification, structural characteristics, and applications in agricultural pest control and grain storage, with emphasis on their mechanisms of action and preparation methods. Key representatives including chitosan, alginate, β-glucan, and pectin function through multiple pathways: direct pest inhibition, induction of plant resistance, bioactive encapsulation, and physical barrier formation. Recent advances in extraction, purification, and advanced nuclear magnetic resonance (NMR) techniques—quantitative NMR (qNMR), diffusion-ordered spectroscopy (DOSY), and pure shift methods—are summarized. Challenges including batch-to-batch variability, high production costs, and regulatory hurdles are discussed and future perspectives on green production, precision structural tailoring, and nano-encapsulation are proposed. This review aims to guide the application of polysaccharide-based materials in insect pest management and food protection.