Comparative study of the physicochemical, microbial, and metabolite changes during kimchi fermentation with different salt types

Considering the increasing concerns over microplastic contamination in sea salt, we evaluated the feasibility of pink salt as a safer and more sustainable alternative in kimchi production. We investigated the feasibility of using pink salt as an alternative to solar salt in kimchi production. Kimchi was prepared with refined salt (RSK), solar salt (SSK), and pink salt (PSK) and fermented at 6 °C for 4 weeks. Fermentation characteristics, including pH, acidity, salinity, texture, microstructure, microbial community, and metabolites, were evaluated. All samples showed similar salinity. RSK reached optimal ripening fastest and showed the lowest yeast and mold counts. PSK maintained the highest texture hardness during fermentation. Scanning electron microscopy revealed severe cell wall damage in RSK, while PSK and SSK exhibited minimal damage. Aerosakkonema funiforme dominated early fermentation, while Latilactobacillus spp. predominated later, with higher abundance in PSK. GC-MS identified 39 metabolites, showing rapid mannitol production in RSK and delayed lactic acid formation in PSK. These results highlight the influence of salt type on fermentation and texture, supporting pink salt as a potential solar salt substitute. • Refined salt kimchi had the fastest fermentation and microbial transition • Pink salt preserved kimchi texture, retaining high hardness and cell wall integrity • Distinct metabolite profiles were driven by salt-dependent microbial activity • Correlations between LAB and metabolites revealed distinct fermentation pathways • Pink salt offers a safer alternative with lower microplastic contamination enhancing kimchi quality.