Changes in Volatile Components during the Steaming Process of Giant Salamander Tails Analyzed by Gas Chromatography-Ion Mobility Spectrometry and Chemometrics

To study the dynamic changes in volatile flavor compounds during the steaming process of giant salamander tail, sensory evaluation, gas chromatography-ion mobility spectrometry (GC-IMS) combined with chemometrics was utilized to analyze the variation of volatile organic compounds after steaming for 0, 2, 5 and 8 min. The results indicated that the sensory score of giant salamander tails was highest after 5 min of steaming. A total of 29 volatile organic compounds were identified, including two alcohols, four aldehydes, three ketones, nine esters, eight ethers, two acids, and one phenol. Compared to those at 0 min, after 2 min of steaming, the contents of esters and ethers decreased, while the relative contents of alcohols and aldehydes increased. As the steaming time increased from 2 to 8 min, the content of esters and aldehydes gradually decreased, while the proportions of alcohols and ethers increased. A stable predictive model was established using partial least squares discriminant analysis (PLS-DA). Based on variable importance in projection (VIP), 10 characteristic volatile flavor compounds were selected from 29 volatile organic compounds (VIP values > 1). These included one alcohol (3-methylbutan-1-ol), one phenol (4-methylguaiacol), three ethers (allyl methyl disulfide, dipropyl disulfide, and isobutyl propyl sulfide), one acid (3-methylpentanoic acid), two aldehydes ((E)2-hexenal, and (E)-2-methyl-2-butenal), and two esters (ethyl acetate and methyl salicylate). Principal component analysis (PCA) showed that the cumulative contribution rate of the first two principal components was 97.6%, allowing for good discrimination of the steaming stages of giant salamander tails based on these differential volatile compounds.