Interpreting metabolite associations and proposed biosynthetic routes in Lactiplantibacillus plantarum-fermented Porphyra haitanensis.

The recent study by Li et al. links Lactiplantibacillus plantarum fermentation of Porphyra haitanensis with enhanced in vitro lipid-lowering-related activities, metabolomic remodeling, and beverage development. We welcome this integrative approach but suggest that the mechanistic interpretation of γ-aminobutyric acid (GABA) and p-coumaric acid (pCA) should be calibrated to the evidence. Untargeted LC-MS supports fermentation-associated changes in relative abundance, yet metabolite identity and concentration require orthogonal confirmation and targeted quantification. Likewise, accumulation of pCA cannot distinguish de novo synthesis from release of pre-existing phenolics or altered turnover, and neither GABA nor pCA was directly shown to mediate the observed enzyme- or micelle-related effects. The marked rise in pancreatic lipase inhibition after formulation and pasteurization further warrants vehicle and pH-matched controls to exclude matrix effects. We propose targeted validation of metabolite identity, flux, enzyme activity, and compound-specific function to strengthen the proposed biosynthetic and functional links.