Variation in Volatile Compounds of Raw Pu-Erh Tea upon Steeping Process by Gas Chromatography–Ion Mobility Spectrometry and Characterization of the Aroma-Active Compounds in Tea Infusion Using Gas Chromatography–Olfactometry–Mass Spectrometry

Abstract

Steeping process is an important factor for aroma release of tea, which has rarely been investigated for the aroma changes of raw Pu-erh tea (RAPT). In addition, the comprehensive aroma characteristics identification of RAPT infusion is necessary. In this study, GC−IMS coupled with principal component analysis (PCA) was used to clarify the difference of volatile profiles during the steeping process of RAPT. Furthermore, the volatiles contained in the RAPT infusion were extracted by three pretreatment methods (HS-SPME, SBSE, and SAFE) and identified using GC−O−MS. According to the odor activity value, 28 of 66 compounds were categorized as aroma-active compounds. Aroma recombination and omission experiments showed that "fatty", "green", "fruity", and "floral" are considered to be the main aroma attributes of RAPT infusion with a strong relationship with 1octen-3-one, 1-octen-3-ol, (E)-2-octenal, β-ionone, linalool, etc. This study will contribute a better understanding of the mechanism of the RAPT steeping process and volatile generation.

Impact of Leavening Agents on Flavor Profiles and Microbial Communities in Steamed Bread: A Comparative Analysis of Traditional Chinese Sourdough and Commercial Yeast

“…30 JMMT2 contained four species with OAVs > 1000, with decanal (citrus, floral) having the highest OAV value (20218), contributing to the floral attributes of CSBs. 31 The presence of 2-ethylhexyl acetate (1049), an earthy herbal aroma not reported in previous studies with a small threshold value (0.043 mg/kg), significantly contributed to the distinctive flavor of CSBs. In SDMT, three compounds with OAVs > 1000 were 3-methyl-1-butanol (18366), ethyl caprate (7436), and gamma-nonanolactone (5266), contributing to fruity, milky, and winy properties of CSBs.…”

“…3-methyl-1-butanol (whiskey, fruity, banana), detected in all four CSBs, contributed significantly to the winey and fruity properties of CSBs as a fermentation product of the Ehrlich pathway . JMMT2 contained four species with OAVs > 1000, with decanal (citrus, floral) having the highest OAV value (20218), contributing to the floral attributes of CSBs . The presence of 2-ethylhexyl acetate (1049), an earthy herbal aroma not reported in previous studies with a small threshold value (0.043 mg/kg), significantly contributed to the distinctive flavor of CSBs.…”

Sensomics-Assisted Characterization of Fungal-Flowery Aroma Components in Fermented Tea Using Eurotium cristatum

“…Therefore, the choice of an appropriate extraction technique becomes the key to analyzing volatile compounds in tea infusion. Extraction of volatile compounds from pu-erh tea using SAFE and SPME methods revealed that SPME can effectively extract ketones, and SAFE can separate highly polar and unstable compounds. − For the first time, SAFE was used to extract volatile compounds from fermented tea by E. cristatum.…”

Aroma release regularities of Rosa damascena from Xuancheng via HS‐GC‐IMS and P&T‐GC–MS

“…As shown in Figure 3, each row shows all the selected signal peaks in one sample, and each column shows the signal peaks of the same volatile compounds in different samples, with brighter colours representing higher contents and darker colours describing lower contents. 10,11 A total of 56 volatile compounds were detected in the rose samples from the three periods, At the same time, their monomers were present in the other two forms (Figure 3). It can be observed that most of these compounds are terpenoids, and these terpenoids bring a terpene-like green, woody aroma to the buds.…”

“…VOCs can be evaluated by gas chromatography-ion mobility spectrometry (GC-IMS) and gas chromatography-mass spectrometry (GC-MS) methods. 10,11 GC-IMS, a highly sensitive technique, does not require any sample pre-treatment and operates only at room temperature, compared to GC-MS, GC-IMS is smaller, easier to instal, does not require a vacuum environment or helium and is more economical, providing a fast and convenient method for rapid sampling after field sampling. [12][13][14] GC-IMS technology has also been used for the detection of food flavouring substances, 15 the characterization of tea flavour, 16,17 the characterization of nasal odour 18 and flower quality monitoring 19,20 and food preservation monitoring.…”