Decoding the evolution of aromatic volatile compounds and key odorants in Suancai (a Chinese traditional fermented vegetable) during fermentation using stir bar sorptive extraction–gas chromatography–olfactometry–mass spectrometry

This study aimed to reveal the evolution of volatile compounds and key odorants in Suancai during two-stage fermentation using stir bar sorptive extraction–gas chromatography–olfactometry–mass spectrometry (SBSE–GC–O/MS). In total, 138 volatile compounds were identified, and 53 aroma-active compounds were detected. The ester composition and alkane and alcohol contents were different in fresh leaf mustard and Suancai in various fermentation stages. During pre-salting, the aroma profile transformed from pungent to salty as the isothiocyanate level decreased. During secondary fermentation, isothiocyanate levels were further reduced, and esters and alcohols with mild aroma were produced, causing the rich and mild aroma of Suancai. Based on the reduced isothiocyanate content and transformed aroma, isothiocyanate may be a key marker for estimating the maturity degree of Suancai. This study provides a theoretical basis for improving the aromatic quality of fermented vegetables. •The evolution of volatile compounds was identified by SBSE-GC-O/MS.•A total of 53 aroma-active compounds were detected by GC-olfactometry.•Two-stage fermentation led to the richer and milder flavor of Suancai.•Isothiocyanate is a key marker for estimating the maturity degree of Suancai.