Recent advances in Citri Reticulatae Pericarpium polysaccharides: Extraction, structure, bioactivity, and...

Citri Reticulatae Pericarpium (CRP), the dried peel of Citrus reticulata Blanco, has a long history of medicinal and culinary use, with aged CRP (≥3 years) valued for its therapeutic and nutraceutical applications. Among one of the main bioactive components of CRP, Citri Reticulatae Pericarpium polysaccharides (CRPPs) have attracted significant attention due to their multifaceted nutritional, pharmacological, and functional properties. This review synthesizes the recent progress in CRPPs research, covering extraction/purification techniques, structural characterization, bioactivities, structure-function relationships, quality control, and industrial potential. Monosaccharide composition of CRPPs varies across different studies: arabinose (Ara), galacturonic acid (GalA), and rhamnose (Rha) are consistently identified as primary components, while others report over ten different monosaccharides in the varying proportions. In addition, their molecular weight (Mw) ranges widely from 1.765 kDa to 7940 kDa, which decreases with the prolonged storage time. CRPPs are heterogeneous polysaccharides with complex structures, which exhibit a spectrum of bioactivities, including antioxidant, immunomodulatory, anti-inflammatory, antitumor, and gut microbiota-modulating effects. However, these bioactivities differs significantly, primarily due to the differences in extraction methods and structural characteristics of CRPPs. Structure-function relationships reveal that α-1,4-glycosidic linkages in GalA-rich CRPP backbones enhance antioxidant activity, β-1,6-branched arabinogalactan side chains mediate immunomodulation, and high branching degrees promote gut microbiota fermentation. This work aims to provide a theoretical foundation for future standardization research and applications of CRPPs in functional foods, therapeutics and related industries.