Lactic acid bacteria fermentation of Undaria pinnatifida: microbial dominance, metabolic remodeling, and quality...

Undaria pinnatifida, a representative brown macroalga, has limited high-value food applications due to its dense cell wall structure, pronounced marine odor, and inefficient conventional processing. In this study, we established a controlled fermentation strategy using different lactic acid bacterial (LAB) starters with Undaria pinnatifida slurry as the substrate. Kimchi starter fermentation was characterized by a predominance of Lactiplantibacillus, whereas milk starter fermentation showed a predominance of Streptococcus. The distinct LAB community profiles were associated with differential patterns of carbohydrate metabolism, amino acid turnover, and lipid-related metabolism, together with changes in flavor profiles and textural properties of fermented Undaria pinnatifida slurry. These findings indicate that starter-dependent microbial community composition was associated with distinct metabolic and quality profiles during fermentation. This study characterizes LAB-associated metabolic patterns and their relationships with quality attributes, providing a basis for the controlled bioprocessing and high-value utilization of brown macroalgae.