Dynamic changes in physicochemical properties and in vitro lipid-lowering function of pectic polysaccharides during pear post-harvest storage

Pectins, as health-promoting factors, often degrade during fruit post-harvest storage. Changes in structure and physicochemical properties of pectic polysaccharides from ‘Huangguan pear’ after 0, 3, and 5 months of 4 °C storage and their lipid-lowering activity were studied. The degree of methylation of pectic polysaccharides decreased from 79.31% to 71.88%. Galacturonic acid content decreased while side chains, molecular weight and viscosity increased, and surfaces became rougher. Decreased binding ability on four bile salts but enhanced inhibitory ability on cholesterol micelles, pancreatic lipase, and cholesterol esterase were displayed. Cell experiments showed pectic polysaccharides reduced total cholesterol and triglycerides levels by downregulating relative mRNA expression of fatty acid synthase (FAS) and sterol regulatory element-binding protein-1c (SREBP-1c), and pears with shorter storage exhibited higher protection against oxidative stress and lipid accumulation in HepG2 cells. Overall, pectin in fresher pears showed more comprehensive lipid-lowering effects, but pears with longer storage still have specific lipid-lowering values.