[Electronic nose, HS-GC-MS, and relative odor activity value reveal odor differences and material basis of...

The Glycyrrhizae Radix et Rhizoma products processed with different methods, including raw materials(S) and products processed with honey according to the method in the Chinese Pharmacopoeia(Z) and Jianchangbang method(M), were analyzed in terms of the odor profile and volatile components by the electronic nose and headspace-gas chromatography-mass spectrometry(HS-GC-MS). The differential components in the three products were screened by chemometrics, on the basis of which the relative odor activity value(ROAV) was adopted to elucidate the odor differences among different products and the material basis of their odors. The results showed that the electronic nose effectively distinguished the products of Glycyrrhizae Radix et Rhizoma processed with different methods. The odor of Glycyrrhizae Radix et Rhizoma before and after processing differed greatly, and the Z and M samples had similar odors. A total of 49 volatile components were identified, including 22, 37, and 32 volatile components in S, Z, and M samples, respectively, among which 14 were common in the three products. There were significant differences in the categories and content of volatile components among different products. The results of principal component analysis(PCA) and orthogonal partial least squares-discriminant analysis(OPLS-DA) confirmed significant differences in the volatile components among products. Twenty-three differential components were screened out with the thresholds of variable importance in projection(VIP) value>1 and P<0.05. The soybean odor of the S samples was analyzed with the ROAV method, which suggested that this odor might be related to the presence of hexanal, 2-pentylfuran, and 1-octene-3-ol. After processing, the content of these components was reduced, and new components such as 3-methylbutanal, 2-acetylpyrrole, and benzeneacetaldehyde were generated. Accordingly, Z and M samples had burnt aroma and honey aroma, respectively. The burnt aroma of Z samples was mainly related to the generation of heterocyclic compounds such as 3-methylbutanal and 2-acetylpyrrole. The honey aroma of M samples was mainly related to the generation of aromatic hydrocarbons such as benzeneacetaldehyde. The use of honey chaff as the auxiliary material may contribute to the richer honey aroma of M samples produced with the Jianchangbang method than that of the Z samples produced with the method in the Chinese Pharmacopoeia.