Abstract: The changes of volatile flavor components during the fermentation of salt radishes with water activities of 0.95, 0.90 and 0.85, respectively simulating the wet, semi-dry and dry state were analyzed by headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). To identify the main components and characteristic volatile components, the data acquired were processed by multivariate statistical analysis (MSA). The results showed that the microflora of wet salted radish was dominated by lactic acid bacteria, while fermentation was very weak or did not occur in the semi-dry and dry state. A total of 61 volatile flavor substances were detected from the three samples fermented for 30 days. Based on principal component analysis (PCA), it was found that 4-methylpentyl isothiocyanate, 1-hexanol, decanal, nonanal, tetrasulfide, dimethyl, acetoin, 1-octen-3-ol, 1-isothiocyanatohexane, 3,5-octadien-2-one, 4-(1-methylpropyl)phenol, 1-heptanol and cis-2-pentenol were identified as typical representatives of the volatile substances. Twelve volatile components were selected with variable importance in the projection (VIP > 1.2) and t-test (P < 0.05) by partial least squares discriminant analysis and hierarchical clustering. Among them, acetic acid was the characteristic component of wet salted radish. 1-penten-3-ol, cis-2-pentenol, 1,1-bis(methylthio)ethane, oxime-, methoxy-phenyl-were the characteristic components of semi-dry salted radish, and hexanoic acid, dimethyl trisulfide, acetoin, 2-pentylfuran, dimethyl tetrasulfide, heptanal, and phenylethyl alcohol were the characteristic components of dry salted radish. These characteristic volatile flavor components could clearly distinguish the three salted radishes. These research results provide a theoretical basis for improving the flavor quality of salted radish.

Key words: salted radish, volatile components, headspace solid phase microextraction-gas chromatography-mass spectrometry, multivariate statistical analysis