# Development of Pretreatment Approaches for Authentic Representation of Tea Infusion Aroma
## 1 Introduction  
Aroma has long been a focal and trending area in flavor chemistry research, with extraction and detection techniques now relatively well-established. Headspace solid-phase microextraction (HS-SPME) is widely employed for aroma extraction due to its simplicity, solvent-free nature, and excellent thermal sensitivity [1, 2, 3]. Gas chromatography-mass spectrometry (GC-MS), as a mature analytical technique, is frequently combined with HS-SPME for aroma studies owing to its minimal sample requirement, high sensitivity, rapid analysis, and strong identification capabilities [4, 5, 6]. To achieve efficient and comprehensive aroma enrichment, previous studies have optimized HS-SPME conditions, identifying key factors such as fiber type, extraction temperature, extraction time, and salt ion concentration. However, optimal parameters vary depending on the analytes or experimental objectives. For instance, [PERSON] et al. [7] found that for a chestnut-like aroma of green tea, the best adsorption was achieved using a DVB/CAR/PDMS fiber at 50 \({}^{\circ}\)C for 50 min, with a fixed tea-to-water ratio of 1 g: 10 mL and an electrolyte concentration of 1-3 mg\(\cdot\)mL\({}^{-1}\). In contrast, [PERSON] et al. [8] reported that for West Lake Longjing tea, optimaladsorption occurred under electrolyte-free conditions, using a DVB/CAR/PDMS fiber at 60 \({}^{\circ}\)C for 30 min with a tea-to-water ratio of 1 g: 50 mL. However, [PERSON] et al. [9] demonstrated that for Dianhong tea, the ideal conditions involved a DVB/PDMS fiber at 70 \({}^{\circ}\)C for 60 min, an electrolyte concentration of 0.33 g:mL\({}^{-1}\), and a tea-to-water ratio of 1 g: 3 mL. Most existing studies prioritize maximizing total peak area or the peak area of key active compounds, often favoring high-temperature, long-duration extraction (e.g., 60 \({}^{\circ}\)C for 60 min [10], 70 \({}^{\circ}\)C for 55 min [11] or 60 min [12], 80 \({}^{\circ}\)C for 60 min [13]) Nevertheless, these processing conditions risk altering sensory profiles, especially in green tea--an aspect that has not been systematically evaluated. Longjing tea, renowned for its emerald color, elegant appearance, mellow aroma, and refreshing taste, is universally acknowledged as the typical representative of green tea. Its distinctive fragrance becomes particularly intense and persistent through high-temperature roasting processes, making it highly prized by consumers and extensively studied by researchers. [PERSON] et al. [14] detected 151 volatile compounds across 29 Longjing tea samples, among which 14 key aroma-active compounds were identified through combined gas chromatography-olfactometry (GC-O) analysis, odor activity value (OAV) calculation, and aroma recombination experiments. The identified compounds include 2-methyl butyraldehyde, dimethyl sulfoxide, heptanal, benzaldehyde, 1-octen-3-ol, (E,E)-2,4-heptadienal, phenylacetaldehyde, linalool oxide I, (E,E)-3,5-octalation-2-one, linalool, nonanal, methyl salicate, geraniol, and \(\beta\)-ionone. Notably, \(\beta\)-Ionone, 1-methylnaphthalene, naphthalene, 2,4-nonadienal, (E)-2-nonenal, and decanal exhibited exceptionally high OAVs (\(>\)1000) and were demonstrated to be primary contributors to the characteristic aroma profile of Longjing tea. [PERSON] et al. [15] employed GC-O and OAV analysis to characterize the aroma profiles of Longjing teas across different grades and geographical origins. (E,E)-2,4-heptadienal, 3-methylbutanal, dimethyl sulfide, linalool, 2-methylbutanal,\(\alpha\)-terpineol, geraniol, dimethyl sulfoxide, furnaceol, and cis-isamone were identified as the primary aroma compounds and (E,E)-2,4-heptadienal, 3-methylbutanal, geraniol, dimethyl sulfide, 2-methylbutanal were considered as the critical aroma-active compounds defining Longjing tea. [PERSON] et al.