Determination of the Volatile Organic Compounds (VOCs) in Mature and Immature Foliage of Five Species of Pinaceae by Gas Chromatography–Mass Spectrometry (GC-MS) with Principal Component Analysis (PCA) and Cluster Analysis (CA)

Conifer needles are rich in resources and have essential ecological and biological functions. However, comparative analysis of the volatile components of immature and mature needles of the family Pinaceae has not been reported to date. In this study, headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (GC-MS) was used to identify the volatile organic compounds (VOCs) in the immature and mature needles of five Pinaceae species. Altogether, 51 VOCs were identified, 31 of which reportedly show biological activity. The identified compounds include alcohols (6), terpenes (35), esters (7), and others (3). Terpenes were the major metabolites (78.38% to 97.18%) in the needles of the conifers. The needles were divided into four categories based on principal component analysis (PCA) and cluster analysis (CA). This is the first study to show a detailed examination of the differences in VOCs between immature and mature conifer needles. Furthermore, immature and mature needles of the five species were distinguished based on their specific VOCs. Our findings provide a reference for the utilization of conifer needles as valuable renewable resources.