Advances in Salt Reduction in Salt-Dependent Traditional Fermented Foods: From Microecological Responses to Flavor and Safety Control.

Salt-dependent traditional fermented foods rely on the selective ecological environment created by salt to develop characteristic flavor, maintain fermentation stability, and ensure product safety. However, the health risks associated with excessive sodium intake have made salt reduction a major priority in this field. This review focuses on representative salt-dependent traditional fermented foods, including soy sauce, fish sauce, shrimp paste, doubanjiang, kimchi, suancai, and fermented olives, and systematically summarizes the multilevel effects of salt variation on fermentation systems. Building on previous reviews of sodium-reduction strategies, flavor perception, and the microbiology of specific fermented food systems, this review integrates physicochemical, microecological, metabolic, and process-stability dimensions into a cross-system mechanistic framework. Salt variation first alters the fundamental physicochemical boundaries of fermentation, including water activity, osmotic pressure, and the ionic environment. It then reshapes substrate degradation, precursor release, and metabolic flux allocation by affecting the salt adaptation of core functional microorganisms, community succession, and microbial interaction networks. These changes ultimately determine endpoint outcomes in flavor formation, safety risk, and process stability. Current evidence suggests that successful salt reduction requires coordinated management of microecological balance, metabolic pathway allocation, flavor compensation, safety assurance, and process stability under reduced-salt conditions. This review further summarizes regulatory strategies involving targeted selection of core functional microorganisms, community reconstruction, stage-specific salt control, flavor compensation, safety assurance, and process early warning, and highlights the need for product-specific, stage-specific, and endpoint-oriented precision salt-control systems.