Exploring the Flavor Substances in “Laocaifu” Based on UPLC-MS Combined With GC-MS

Abstract

Background: Laocaifu (LCF), a traditional Chinese fermented radish product originating from the Fujian and Chaoshan regions, is widely consumed for its distinctive flavor and texture. However, the specific flavor substances and quality markers associated with different aging periods still remained poorly characterized.

Purpose: This study aimed to characterize the key flavor substances and quality markers in LCF across different aging durations.

Methods: The chemical profiles of LCF samples aged 2, 6, 10, 20, and 30 years were comparatively characterized using ultraviolet (UV), high-performance liquid chromatography (HPLC), ultra-performance liquid chromatography–mass spectrometry (UPLC–MS), and gas chromatography–mass spectrometry (GC–MS) methods. Simultaneously, sensory evaluation was performed to analyze the changes of color, aroma, flavor, and texture characteristics of LCF at different years; to verify the differences of flavor substances; and to provide a sensory basis for subsequent chemical analysis.

Results: Sensory evaluation revealed progressive darkening of color, intensification of sourness, and softening of texture with extended aging of LCF. HPLC assay identified potential signature components eluting at 14–16 min, while UPLC–MS assay detected acid derivatives (such as azelaic acid and hexadecanedioic acid) and alcohols as major flavor contributors. Notably, hexadecanedioic acid and azelaic acid showed a strong positive correlation with prolonged aging, establishing their potential as a reliable aging biomarker. Age-dependent variations in ester and alcohol contents were observed, especially in LCF at 6 and 10 years, suggesting their influence on sensory characteristics. Furthermore, GC–MS assay showed that compositional diversity increased with the aging time of LCF.

Conclusion: This study successfully established UPLC–MS as an effective tool for LCF quality assessment by correlating chemical profiles with sensory attributes. The identification of hexadecanedioic acid and azelaic acid as key aging biomarkers, with content directly proportional to fermentation duration, provided a scientific basis for quality control and market differentiation of LCF products. These findings address critical gaps in the commercial characterization of this traditional fermented food.