Rheological properties, molecular distribution, and microstructure of Fortunella margarita (Lour.) swingle polysaccharides.

Fortunella margarita polysaccharides (FMPS) are one of the main bioactive components of F. margarita. The activity is related to their rheological properties and structure. The objective of this study was to investigate the relationship between rheological properties, molecular distribution, and microstructure of crude FMPS (C-FMPS) and purified FMPS (P-FMPS). The results showed that both of solutions were shear-thinning pseudoplastic fluids with flow properties in line with the Power Law model. The pseudoplasticity of P-FMPS was stronger compared to C-FMPS. Additionally, the molecular weight and polydispersity of P-FMPS were greater, whereas the molecular radius was less compared to C-FMPS. The surface of C-FMPS was rough and dense whereas P-FMPS displayed a smooth network structure by environment scanning electron microscopy. According to confocal laser scanning microscopy, C-FMPS dispersed in the medium without connected network, whereas the network of P-FMPS was unevenly distributed in the medium and the shape was compact and smooth. The molecular distribution and microstructure of P-FMPS were attributed to the purification process while rearrangement and aggregation of polysaccharide molecules took place, which resulted in the significant difference of rheological properties between C-FMPS and P-FMPS.

Molecular Structural Characteristics of Polysaccharide Fractions from Canarium album (Lour.) Raeusch and Their Antioxidant Activities.

UNLABELLED: The objective of this study was to investigate the multiple relations between the preliminary molecular structural characteristics and antioxidant activities of polysaccharides from Canarium album (Lour.) Raeusch (CPS). Three polysaccharide fractions, CPS1, CPS2, and CPS3, were isolated from CPS by column chromatography. CPS1 and CPS3 were mainly composed of neutral polysaccharides linked by α- and ß-glycosidic linkages while CPS2 was pectin polysaccharides mainly linked by ß-glycosidic linkages. According to the SEC-MALLS-RI system, the molecular weight of CPS1 was greater compared to CPS2 and CPS3, and the molecular weight and radius of CPS did not display positive correlation. The chain conformation analysis indicated CPS1 and CPS2 were typical highly branched polysaccharides while CPS3 existed as a globular shape in aqueous. Furthermore, the antioxidant activity of CPS2 was better than that of CPS3, while that of CPS1 was the weakest. The antioxidant activities of polysaccharide fractions were affected by their monosaccharide composition, glycosidic linkage, molecular weight, and chain conformation. This functional property was a result of a combination of multiple molecular structural factors. CPS2 was the major antioxidant component of CPS and it could be exploited as a valued antioxidant product. PRACTICAL APPLICATION: The molecular structural characteristics, antioxidant activities, and structure-function relationships of polysaccharide fractions from Canarium album were first investigated in this study. The results provided background and practical knowledge for the deep-processed products of C. album with high added value. CPS2 was the major antioxidant component of CPS, which could be exploited as a valued antioxidant ingredient in food and pharmaceutical industries.