Volatile Constituents of Some Selected Plant Species Traditionally Used as Tea in the Sharri Mountains (Kosovo)

The study evaluates the chemical composition of the volatile constituents of ten plant species traditionally used as herbal tea in the Sharri Mountain regions (Kosovo and North Macedonia). Volatile constituents responsible for the flavour and fragrance of selected species (Crataegus monogyna, Cydonia oblonga, Malus sylvestris, Matricaria chamomilla, Morus alba, Morus nigra, Rosa canina, Sambucus nigra, Tilia cordata, and Vaccinium myrtillus) were separated and then identified using GC-MS, whereas GC-FID is employed for the quantitative analysis. Experimental data revealed different patterns of volatile constituents depending on plant species. Monoterpenes, sesquiterpenes, diterpenes, and norisoprenoids were the most abundant volatile constituents. Principal component analysis (PCA) was deployed for data analysis and resulted in grouping these ten species in four principal clusters. The combination of various volatile constituents present in specific plant species may play an important role in the specific aroma and taste sensation of these species used as recreational teas.


Introduction
e Sharri Mountain (in Albanian known as Malet e Sharrit; in Macedonian and Serbo-Croatian asŠar Planina) lies in the southern part of Kosovo and northwest part of North Macedonia. e region is rich in terms of biological diversity, and in recognition of its biodiversity richness, a part of Sharri Mountain in Kosovo (1989Kosovo ( , extended in 2012 and that in North Macedonia (2021) were declared as a National Park [1][2][3]. e region possesses valuable cultural heritage, too [1]. e ethnobotanical literature revealed that local communities used local plants as food and as aromatic and refreshing hot beverages (recreational tea) apart from medicinal purposes. Species of the Lamiaceae, Asteraceae, and Rosaceae families were mainly used to prepare herbal tea [4]. In this study, the chemical composition of the volatile constituents of ten local plant species used as recreational tea in Kosovo

Plant
Material. e plant material was collected from July to October 2018 in Sharri Mountains (Kosovo and North Macedonia). Only plant species used as hot aromatic beverages (water infusion) for recreational consumption (excluding those used for specific medical purposes) were selected. ey were selected based on the reviewed data from previously published ethnobotanical studies, unpublished ethnobotanical data, and interviews carried out during the fieldwork. Plant material was either collected from wild populations in Sharri Mountains, purchased in the local markets (in 2018), or provided by local residents that were wildcrafted or cultivated for family use. e plant species were identified according to the Flora Europaea [5], while the botanical nomenclature assignments followed e Plant List database [6].

Plant Material Extraction.
Plant material was dried, cut into small pieces (>0.3 cm), and then extracted by hydrodistillation (50g of cut plant material in 0.5 litres of deionized water contained in a 1 litre flask) at a distillation rate of 3 ml.min −1 using a Clevenger apparatus for 3 hours. eir volatiles were collected in 1 mL n-hexane, and the extracts were stored at −18°C in the freezer until further analysis.

GC-MS and GC-FID Analyses.
e volatile constituents were separated using a HP-5ms column (30 m × 0.25 mm i.d., film thickness 0.25 mm) in a gas chromatograph (Agilent 7890A). e identification was made using a mass spectrometry detector (Agilent 5975C MSD). e mass spectrometer ionization energy was 70 eV, with a mass range of 40-400 m/z. Helium was used as a carrier gas at an initial flow rate of 0.6 mL/min (50 psi), and 1.0 μL of the sample was injected with a split ratio of 50 : 1. e initial GC oven temperature was 60°C (5 min), increased from 60°C to 280°C at a rate of 5°C/min. GC-FID analyses were performed with the same column and temperature program as the analytical GC/MS.

Identification of Volatile Constituents.
Each constituent was identified by comparing the Kovats retention indices with those reported in the literature [7]. e retention arithmetic indices (RIs) were calculated using a linear interpolation of a homologous series of n-alkane (C9-C28) retention times under the same operating conditions. Furthermore, the constituents were identified by comparing the mass spectra of each constituent with those stored in the NIST 08.L and WILEY MS 9th databases. Furthermore, some of the peaks were identified by comparing the retention times and mass spectra with authentic constituents. e relative intensity of each compound has been calculated as the ratio between the area of the specific molecule and the sum of the areas of all identified peaks (peak area normalization method) in the chromatogram [8,9].

Statistical Analysis.
Principal component analysis (PCA) was used for data analyses. Only chemical constituents with concentrations higher than 5% were selected for statistical analysis. e XLStat program (version 2021.2.2) was used for the PCA.

Conclusions
Eighteen plant species were identified to be used as recreational herbal teas in the Sharri Mountain area. e chemical composition of eight plant species (Lamiaceae family) was reported previously, while in this article, the volatile constituents of the species belonging to the families of Adoxaceae, Asteraceae, Ericaceae, Malvaceae, Moraceae, and Rosaceae are reported. Experimental data revealed different patterns of volatile constituents depending on plant species. e variety of volatile constituents present in plant species suggests that their combination may play an important role in the specific aroma and taste sensation of recreational teas, and these factors are important for consumers' preferences. On the other hand, besides phytochemical characteristics, evaluating the pharmacological and nutritional properties of plants used for the tea preparation is needed to warrant their safe and appropriate use, especially for those teas consumed regularly.

Data Availability
e GC-MS data used to support the findings of this study are available from the corresponding author upon request.