OBJECTIVE  To compare the differences of volatile components in processed products before and after Rehmanniae Radix processing and different processing methods.

METHODS  Headspace-gas chromatography-ion mobility spectrometry(HS-GC-IMS) was used to detect and compare the volatile components of Rehmanniae Radix raw products and their processed products wine-stewing processed Rehmanniae Radix Praeparata and steamed Rehmanniae Radix Praeparata, and the differences in volatile components were analyzed by principal component analysis(PCA) and nearest neighbor fingerprint analysis.

RESULTS  GC-IMS fingerprints showed that there were differences in the volatile components of Rehmanniae Radix raw products and processed products, and there were also significant differences in the volatile components of wine-stewing processed Rehmanniae Radix Praeparata and steamed Rehmanniae Radix Praeparata obtained by different processing methods. A total of 90 volatile components were identified. The characteristic components of Rehmanniae Radix before and after processing, and the different components between stewed Rehmanniae Radix and stewed Rehmanniae Radix were determined. The contents of 2-methylpropionic acid, butyric acid, 2-methylpropanaldehyde, ethyl lactate, β-pinene, ethanol, 1-propanol, 2-methyl-1-propanol, 3-methyl-1-butanol, 1-hexanol, 2-amylfuran and other substances in wine-stewed precessed Rehmanniae Radix Praeparata were higher. The contents of E-2-pentenal, thiophene, 2-methylpyrazine, 2-pentanone, cyclohexanone, 4-methyl-2-pentenone, 4-methyl-3-pentene-2-one, isopropyl acetate and other substances in steamed Rehmanniae Radix Praeparata were higher. The results of PCA and "nearest neighbor" fingerprint analysis showed that the separation between raw Rehmanniae Radix and its processed products and wine-stewing processed Rehmanniae Radix Praeparata and steamed Rehmanniae Radix Praeparata was good.

CONCLUSION The volatile components of Rehmanniae Radix have changed greatly before and after processing, and the results of this study can provide some ideas for the identification of Rehmanniae Radix products and there processed products, and provide a reference for the quality control and clinical application of Rehmanniae Radix decoction pieces.