Volatile Components’ Variation Analysis on Ginseng Stems and Leaves at Different Growth Ages by HS-SPME-GC-MS

Abstract

Panax ginseng is a famous valuable folk herb, the price of which particularly depends on its cultivation age. Since the classical chemical analysis usually needs to destroy the plants which is not suitable for the old wild ginseng due to the huge cost, in the current study, we employed the headspace solid-phase microextraction (HS-SPME) GC-MS methodology which has the advantage of time-saving, nondestructive, and green to analyze the growth age of ginseng (roots) via determining the volatile components of ginseng stem and leaves (GSLs) combined with metabolic profiles way. 100 mg of finely ground GSL samples (3–7 years) were extracted by a 65 μm PDMS-DVB fiber in the headspace and then analyzed within 20 mins. The content assay of total saponins, crude polysaccharides, and total protein was also included. As a result of GC-MS-based profiling, the orthogonal partial least-squares discriminant analysis’ (OPLS-DA) score plots showed excellent classification of four comparison groups (the 3- and 4-, 3-and 5-, 3- and 6-, and 3- and 7-year-old GSL) with 100% discrimination rate, respectively. 263 common differential variables were gained referring to the VIP and P values. 32 volatile metabolites were identified and showed good age discrimination capacities with an area under the curve (AUC) value of more than 0.8 by the receiver operating characteristic (ROC) analysis. Remarkably, there was one volatile component of sesquiterpenes, 1-cyclohexene-1-carboxaldehyde, 2, 6, 6-trimethyl-, which showed an excellent prediction with the AUC value of 1.0 among all the four compared groups, which could be the potential biomarker to distinguish all the four compared groups. The total contents of different growth ages of components of ginseng stems and leaves were distinct. The contents of total protein (4.80 ± 0.27%) and crude polysaccharide (24.15 ± 0.89%) in the 4th year of GSLs were the highest among the five cultivation years. The content of total saponins (4.66 ± 0.38%) in the 5th year of GSLs was the highest. These results could provide a novel reference for the GSLs’ harvest and application periods. Moreover, the current study could also supply a promising way to set up a nondestructive, in situ, and green approach to discriminate the growth age of Panax ginseng rapidly without digging the roots out instead of detecting the VOCs of GSLs.