# Development of Pretreatment Approaches for Authentic Representation of Tea Infusion Aroma
## 4 Discussion  
Tea aroma evaluation typically combines hot sniffing (60-80 \({}^{\circ}\)C), warm sniffing (25-55 \({}^{\circ}\)C), and cold sniffing (<25 \({}^{\circ}\)C) [26]. Hot sniffing captures high-boiling-point volatiles and off-odors but may impair olfactory sensitivity due to thermal stimulation. Cold sniffing assesses aroma persistence after cooling, while warm sniffing demonstrates superior evaluation accuracy, offers higher accuracy for evaluating dominant aroma characteristics and harmony. Thus, 30-60 \({}^{\circ}\)C represents the critical temperature range for aroma quality assessment and extraction parameter selection. In aroma recombination studies, solutions are often equilibrated at 25 \({}^{\circ}\)C [33,34] for olfactory validation, as no further aroma changes occur at this temperature. However, during HS-SPME extraction, prolonged high-temperature exposure may alter aroma profiles--a previously overlooked issue. Our methodology was developed by synthesizing the temperature for aroma evaluation while ensuring maximal preservation of aroma integrity during extraction and testing both pure and ionized water systems, ensuring methodological accuracy, specificity, and innovation. Validation tests confirmed that ionic systems exhibited lower stability than pure water, suggesting greater susceptibility to extraction conditions and underscoring the need for optimized protocols when analyzing ionized-water-infused aromas. However, in both ionic aqueous and pure water systems, extraction at 30 \({}^{\circ}\)C was found to minimize alterations in the aromatic profile before and after extraction, thereby representing the optimal temperature for screening high-fidelity extraction conditions. [PERSON] et al. investigated the aroma characteristics of Longjing tea using HS-SPME-GC-MS with extraction conditions of 60 \({}^{\circ}\)C for 60 min, identifying 10 key compounds significantly contributing to its aroma quality [14]. However, this study did not optimize the extraction parameters. [PERSON] employed the HS-SPME-GC-MS methodology to compare different extraction temperatures (25, 35, 45, 55 \({}^{\circ}\)C) and durations (20, 40, 60, 80 min) for green tea infusion, concluding that 45 \({}^{\circ}\)C for 60 min provided optimal recovery of typical aroma components [35]. Notably, this work did not consider aroma fidelity as a factor, resulting in different optimal conditions from those identified in our current study. Our research group's previous analysis of Longjing tea infusion aroma adopted high-fidelity extraction conditions (30 \({}^{\circ}\)C, 30 min) [23], which led, however, to a relatively low content of aromatic compounds. The present study reveals that while the tea-to-water ratio positively affects aroma enrichment, it has minimal impact on fidelity. Therefore, increasing the brewing ratio could be strategically employed to enhance extraction efficiency when sample quantity or budget permits, without compromising aroma authenticity. An extraction duration of 30-45 min was determined to be the safe window for preserving genuine aroma characteristics, and this can be adjusted for experimental efficiency. Notably, under high-temperature, long-duration conditions (60 \({}^{\circ}\)C, 60 min), ionized water systems exhibited higher total aroma enrichment than pure water but with intensified off-flavors. This phenomenon could be leveraged in mechanistic studies to amplify ionic effects and identify key odorants influenced by mineral content. Although the high-fidelity conditions successfully preserved the authentic aroma profile and enabled precise quantification for aroma recombination experiments, the lower extraction yield compared to high-temperature/long-duration methods may obscure subtle differences in aroma content caused by varying ionic content.