Analysis of the Difference of Volatile Substances in Sprouted Garlic Based on Electronic Nose and GC-MS

In order to investigate the differences of volatile compounds in sprouted garlic, an electronic nose and trap headspace-gas chromatography-mass spectrometry (HS-Trap-GC-MS) combined with orthogonal partial least squares discriminant analysis (OPLS-DA), aroma activity value, differential heat map, and correlation analysis were employed to analyze the differences in volatile compounds of garlic sprouts at 0, 24, 48, 72 and 96 hours. A predictive model with a prediction accuracy of 96.00% was established by combining the electronic nose with OPLS-DA. GC-MS analysis revealed that sulfur compounds were the major common volatile compounds in garlic sprouts at different sprouting stages. The relative content of sulfur compounds showed a decreasing trend with the prolongation of sprouting time, while the variety exhibited an increasing trend. Allyl disulfide was the compound that experienced the most significant decrease in content during the sprouting process. Allyl tetrasulfide and allyl mercaptan were identified as common key compounds in the samples. Differential heat map analysis demonstrated that in addition to differences in the content of common substances, the absence of propyl sulfide, hexanal, di-tert-butyl dicarbonate, propenol, 6-methyl-2-heptyne, 5-methylthiadiazole, 2-ethy-1,3-dithiane, 2-prop-2-ynylsulfonylpropane, 2,5-dimethylthiophene, 2,5-dimethylfuran, 1-hexen-3-ol, and 1,3-dithiane further amplified the differences in odor between non-sprouted and sprouted garlic. The types of main common volatile compounds in sprouted garlic showed an increasing trend with the extension of sprouting time. There was a significant correlation between the major volatile compounds of garlic and most sensors of the electronic nose. The odor intensity of garlic gradually decreased with the prolongation of sprouting time.