Profiling Real-Time Aroma from Green Tea Infusion during Brewing

Abstract

Aroma substances are the most crucial criteria for the sensory evaluation of tea quality, and also key attractors influencing consumers to make the decision for purchasing tea. Understanding the aromatic properties of tea infusion during different brewing time is crucial to control the tea aromatic quality. Here, headspace and direct immersion solid-phase microextraction (HS-SPME and DI-SPME), coupled with GC-MS, were employed to investigate the impact of brewing time on the changes of the volatile features of green tea infusion. Esters, aldehydes, alcohols, fatty acids, and alkaloids were the predominant volatile groups from tea infusions. Two to three minutes was identified as the best duration for the tea brewing that can maximize the abundance of aromatic chemicals in the headspace emitted from the tea infusions. The variation of the key aromatic contributors between the tea infusion and the headspace over the infusion tended to equilibrate during the tea brewing process. This study provides a theory-based reference method by analyzing the real-time aromatic characteristics in green tea. The optimal time was determined for aromatic quality control, and the complementary relationship between the volatiles in the headspace and its counterpart, tea infusion, was primarily elucidated.

Optimization of Brewing Process Vine Tea and Flavor Analysis of Different Brewing Processes

“…Te phase equilibrium of the tea-water system consists of three primary components: water, tea leaves (including soluble and insoluble tea solids), and headspace. In essence, the system tends to achieve equilibrium during the brewing process, involving the release of volatile organic compounds (VOCs) from tea leaves into the tea infusion, as well as the subsequent difusion of these VOCs from the tea infusion into the headspace through a series of thermophysical and chemical reactions [61]. Furthermore, the properties and the percentage of the compounds in tea leaves, especially soluble substances, as well as the brewing conditions, played crucial roles in this step.…”

“…Tis equilibrium is dynamically maintained during the infusion process, as volatile organic compounds (VOCs) are released from the tea leaves into the tea infusion and VOCs are emitted into the headspace through thermophysical and chemical reactions. It is important to note that the nature and percentage of compounds in the tea leaves, particularly soluble substances, as well as the brewing conditions, play a signifcant role in determining the outcome of this phase equilibrium [53].…”

“…All potential compounds under various brewing conditions were then listed and those with a retention index greater than 90 were selected, as detailed in Table 7. It has been observed that vine tea may contains 45 diferent odorants, with 7 main compounds including terpenes, olefns, alkanes, alcohols, aldehydes, esters, ethers, and ketones [60,61]. From the organoleptic description, 23 compounds were identifed as "sweet," indicating that the primary favor of vine tea is sweet.…”

Characterization of Key Odorants in Lushan Yunwu Tea in Response to Intercropping with Flowering Cherry

“…Peak identification was performed by searching the mass spectra in the National Institutes of Standards and Technology Mass Spectrometry (NIST MS) library and comparing their retention indices (RIs) with published data using the same capillary column [25]. An n-alkane standard (10 µg/mL) was injected under the same GC conditions as the external standard.…”

Identification of volatile compounds and metabolic pathway during ultrasound-assisted kombucha fermentation by HS-SPME-GC/MS combined with metabolomic analysis

“…Invertase, a secreted enzyme by yeast decomposed the sucrose in tea fungus into glucose and fructose. Green tea is fermented using Saccharomyces cerevisiae and it might increase the key aroma compounds(linalool and 2-phenyl ethanol) by 1.3 times and 10 times, respectively, to yield fermented green tea with a fruity aroma [4] . At the same time, it further synthesizes ethanol via glycolysis.…”