Integrated VOC and non-VOC profiling for stage-specific quality assessment of kimchi fermentation using LC-MS/MS and...

Kimchi fermentation by lactic acid bacteria (LAB) produces dynamic metabolites influencing its flavor and quality. This study aimed to identify fermentation-stage-specific indicator markers by quantifying non-volatile metabolites, including lactic, citric, malic acids, and arginine using LC-MS. These compounds were effective in characterizing the initial fermentation stage, as their concentrations declined significantly by week 2, when Leuconostoc species dominated initial fermentation before the microbial community transitioned to Lactobacillus species from week 3 onward. However, non-volatile analysis was limited in differentiating the middle and last stages. Among low-molecular-weight VOCs such as 1-hexanol, butanal, hexanal, 2-butanone, and 2,3-pentanedione remained stable during weeks 2-4, indicating an optimal ripening stage, while significant shifts in VOCs profiles occurred after week 6, marking the overripening stage. Additionally, 1-hexanol and 2,3-pentanedione contributed to the flavor from the middle to the last stage. The multi-indicator approach allows precise stage classification and supports standardized kimchi fermentation and quality control.