Chemometrics-based GC/MS analysis of black tea volatiles from different regions of Iran

The current study aimed to obtain an informative chemical signature of the volatile fraction of black tea samples from the main areas of tea cultivation in Iran. Tea is the most popular flavored and functional drink consumed worldwide which has received considerable attention regarding its high consumption and beneficial effects on human health. Tea aroma is one of the most important factors determining this safe drink s quality, origin traceability, and general acceptability. In order to obtain an informative chemical signature of the volatile fraction of black tea samples the chemical consequents and relative content of volatile compounds of Iranian black tea samples from four different typical geographical origins were comprehensively analyzed on the basis of headspace solid-phase microextraction gas chromatography–mass spectrometry (HS–SPME–GC– MS) technology combined with chemometric analysis .A multivariate curve resolution method is applied to resolve and recover the pure response profiles. Multivariate curve resolution-alternative least squares (MCR-ALS) algorithm as an iterative method has been employed combined with this gas chromatographic procedure for resolving the overlapped and embedded peaks and overcoming some challenging fundamental chromatographic problems occurring during GC-MS analysis; an overall volume integration (OVI) technique was also used for the semi-quantitative analysis to obtain the relative concentrations of chemical constituents. GC-MS analysis using chemometric tools resulted in extending the number of identified constituents from 71 to 130 components with concentrations higher than 0.01%. It was found that β-Ionone (7.51%), was the most abundant aroma component, followed by Tridecane (7.44%), Linalool (5.51%), β- Phellandrene (5.48%), Dodecane (5.45%), cis-Geraniol (4.73%), 1,2-Epoxylinalool (4.68%), Linalool oxide (4.45%), and α-Farnesene (4.1%). This is the first report to identify the volatile compounds of Iranian black tea, which improves the identification and authentication of this complex natural product.