Improving the physicochemical and in vitro hypolipidemic properties of soluble dietary fiber in camellia seed residue by a cellulose degrading fungus YC49

Camellia seed residue (CSR) is the main by-product after edible oil extraction from camellia seed, which is a potential low-cost source of soluble dietary fiber (SDF). However, the lower yield and functional properties limit the further application of CSR SDF in the food industry. To fully utilize this resource, in this study, the cellulose degrading fungus YC49 was screened and used to modify SDF in CSR. After fermentation with YC49, the physicochemical structure and in vitro hypolipidemic properties of CSR SDF were improved. Scanning electron microscopy, X-ray diffraction, molecular weight distribution and flow properties showed that fermentation endowed F-SDF (after fermentation) with a more porous microstructure, lower crystallinity, smaller molecular weight and higher viscosity. The results of monosaccharide composition and Fourier transform infrared spectroscopy pointed to differences in the monosaccharide percentages and functional group types between CK-SDF (control) and F-SDF. These alterations combined to achieve improvements in the hydration properties and hypolipidemic activities of CSR SDF, including water holding capacity, oil retention capacity, cholesterol adsorption capacity, pancreatic lipase inhibition capacity, and bile acid binding capacity. Overall, the results indicated that YC49 could be used as an ideal strain for the fermentation modification of SDF in CSR, and F-SDF has the potential to serve as a hypolipidemic component in functional foods.