Desalination and flavor improvement of fish sauce via electrodialysis with charge-selective nanofiltration membranes

Reducing sodium in fish sauce without weakening its characteristic umami and fermented aroma remains a major challenge for high-salt condiments. Here, electrodialysis with charge-selective nanofiltration membranes (ED-csNF) was evaluated as a selective desalination strategy capable of coupling ion removal with flavor retention and remodeling. ED-csNF significantly reduced salt content by 77.82%, while AAN increased from 0.83 to 0.98 g/100 mL, total FAAs from 58.67 to 91.26 mg/g, and total organic acids from 43.95 to 61.96 mg/g. In addition, the major umami amino acids, glutamic acid and aspartic acid, increased from 6.32 to 11.05 mg/g and from 4.86 to 8.66 mg/g, respectively. Sensory analysis confirmed a shift from a salty, fishy, and ammoniacal profile toward stronger umami, meaty, and soy sauce-like notes. Flavor analysis showed that ED-csNF selectively enhanced desirable aroma compounds, including alcohols, esters, ketones, and phenols whereas typical off-note compounds such as dimethyl trisulfide and several pyrazines were reduced. These results demonstrate that ED-csNF functions not only as a sodium-reduction technology but also as a flavor-selective processing platform for producing low-sodium fish sauce with enhanced sensory quality.