Characterization of the key aroma compounds in Longjing tea using stir bar sorptive extraction (SBSE) combined with gas chromatography-mass spectrometry (GC–MS), gas chromatography-olfactometry (GC-O), odor activity value (OAV), and aroma recombination

Characterization of the key aroma compounds in Laoshan green teas by application of odour activity value (OAV), gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and comprehensive two-dimensional gas chromatography mass spectrometry (GC × GC-qMS)

Aroma is one of the most important criteria of tea quality, but the dynamic changes of aroma profile during the manufacturing process, and the chemical basis of characteristic aroma in Fu brick tea remain largely unknown. In this study, a total of 72 volatiles were identified and quantified, only the esters content increased sharply during the process. Sensory quantitative description analysis revealed that the ‘green’ attribute was dominated in the early processing stage, and the ‘fungal flower’, ‘flower’, ‘mint’ and ‘woody’ attributes became the major contributors to the aroma character in the later processing stages. Indicated by partial least-squares analysis, the linalool, acetophenone, and methyl salicylate were identified as key volatiles contributors to the ‘fungal flower’, ‘flower’, and ‘mint’ attributes, the cedrol contributed to ‘woody’ attribute, and twelve alcohols and aldehydes were related to ‘green’ attribute. Besides, bidirectional orthogonal partial least squares analysis revealed that six fungal genera Aspergillus, Candida, Debaryomyces, Penicillium, Unclassified_k_Fungi, Unclassified_o_Saccharomycetales were identified as core functional microorganisms link to the metabolism of volatiles. Taken together, these findings provide new insights into Fu brick tea aroma profile variation and increase our understanding of the formation mechanism of the characteristic aroma during the manufacturing process.

Characterization of the key aroma compounds and microorganisms during the manufacturing process of Fu brick tea

Enantiomeric and quantitative analysis of volatile terpenoids in different teas (Camellia sinensis).

A comparative study of volatile components in Dianhong teas from fresh leaves of four tea cultivars by using chromatography-mass spectrometry, multivariate data analysis, and descriptive sensory analysis.

Dark tea is a special type of tea that requires microbial fermentation during the post-fermentation process, and its volatile composition is quite different from other tea kinds. The present study aimed at charactering the volatile composition of two typical Chinese dark teas (Fu-brick tea and Pu-erh tea). Volatile compounds from both teas were extracted and analyzed using simultaneous distillation extraction (SDE) combined with two-dimensional gas chromatography-time-of-flight-mass spectrometry (GC × GC-TOFMS). A total of 373 and 408 major aromatic components were tentatively identified in Fu-brick tea and Pu-erh tea, respectively. The relative quantification results showed that ketenes (24.87%), ketones (16.86%), aldehydes (14.36%) and olefine aldehydes (9.11%) were more abundant in Fu-brick teas, while in Pu-erh teas, ketenes accounted for 17.95%, followed by aldehydes (14.51%), ally esters and ketones (11.94% and 10.78%). Multivariate analysis indicated that obvious differences existed in the levels of some aromatic compounds between the two dark teas. Benzaldehyde and benzeneacetaldehyde in Fu-brick teas were considerably lower and accounted for approximately 55% of those in Pu-erh teas; whilst, nonanal and 2-hexenal in Fu-brick tea were twice as high as in Pu-erh tea. The application of pre-enrichment extraction with GC × GC-TOFMS analysis gives a thorough view of the aromatic constituents of dark teas.

Volatile composition of Fu-brick tea and Pu-erh tea analyzed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry

Enantiomeric analysis of linalool in teas using headspace solid-phase microextraction with chiral gas chromatography

In the present study, volatile compounds from 15 yellow tea samples were extracted and examined using stir bar sorptive extraction (SBSE) combined with gas chromatography-mass spectrometry (GC-MS), and the key odorants were identified by gas chromatography-olfactometry (GC-O) analysis. Results revealed 74 volatile compounds in these yellow teas, geraniol (3.89 μg/g) being the most abundant aroma compound. Alcohols and esters were the dominant volatiles, accounting for approximately 52.44% of the total volatiles in content. Moreover, 25 key odorants were identified by GC-O method, and were considered to be responsible for the unique aroma quality of yellow tea. Major key odorants included (E, E)-3,5-octadien-2-one, (Z)-linalool oxide (furanoid), (E)-2-heptenal, naphthalene, geraniol, (E)-linalool oxide (furanoid), styrene, linalool, α-ionone, 1-octen-3-ol, trans-β-ionone, and (E, Z)-3,5-octadien-2-one. In addition, huge differences were observed among the content levels of key odorants in three types of yellow tea samples, namely MengDingHuangYa (MDHY), WeiShanHuangCha (WSHC), and PingYangHuangTang (PYHT). This is an important study describing the characterization of aroma and key odorants in yellow tea. The results obtained from this study advance our understanding of the aroma quality of yellow tea, thereby providing a theoretical basis for the processing and quality control of yellow tea aroma quality.

Hai-Peng Lv

Papers

Volatile composition of Fu-brick tea and Pu-erh tea analyzed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry

Enantiomeric analysis of linalool in teas using headspace solid-phase microextraction with chiral gas chromatography

Volatile components and key odorants of Chinese yellow tea (Camellia sinensis)