Effect of Lactic Acid Bacteria Fermentation on the Structural Characteristics and Functional Properties of Bangia fuscopurpurea Dietary Fiber

In this study, the chemical composition, functional properties and in vitro anti-glycation activity of dietary fiber extracted from raw Bangia fuscopurpurea (control) and fermented B. fuscopurpurea with lactic acid bacteria (LBDF) were systematically investigated. The results indicated that compared with the control sample, LBDF showed a significant increase in soluble dietary fiber content and a 14.34% increase in water-holding capacity (WHC). Moreover, LBDF exhibited remarkable hypoglycemic activity, with a glucose dialysis retardation index (GDRI) of 38.81% and an α-glucosidase inhibition rate of 69.13%. It also demonstrated significant lipid-lowering effects, with a cholesterol binding capacity of 99.12% at pH 2.0 and a pancreatic lipase inhibition rate of 70.61%. Furthermore, LBDF effectively mitigated oxidative stress damage in HT29 cells induced by advanced glycation end products (AGEs) and significantly decreased the expression levels of pro-inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). These functional improvements may be ascribed to structural alterations resulting from lactic acid bacterial fermentation, including increased soluble dietary fiber content, the formation of a rough and porous structure, and the exposure of active groups. This study not only provides a theoretical basis for the high-value utilization of B. fuscopurpurea, but also confirms the application potential of lactic acid bacterial fermentation in improving the quality of seaweed dietary fiber.