## 1 Introduction  
Tea is one of the most consumed non-alcoholic beverages worldwide after water. Due to its pleasant taste, attractive aroma, and health-promoting effects [1; 2; 3], more than two billion people in approximately 170 countries and regions drink tea. According to the manufacturing techniques and sensory qualities, tea can be classified into six different types, including green, white, yellow, oologn, black and dark tea [4]. Green tea is a nonfermented tea and is usually produced from small-leaf tea cultivars (_Camellia sinensis_ var. _sinensis_) [5]. The primary manufacturing processes for green tea include spreading, fixing, rolling, and drying, which maintain the color of the infusion and leaves green. Fixing is the feature of green tea manufacturing and is crucial for high-quality green tea, which must follow the rules of fast, even, and high-temperature. The aims of fixing are to deactivate enzymes in tea shoots for maintaining a green color, to promote the development of volatile compounds, and reduce moisture content [4]. In China, green teas are classified as roasted, baked, steamed, and sun-dried green tea based on the fixing and/or drying methods [6]. Tea shoots are rich in volatile and non-volatile compounds that determine the flavor quality of processed tea. Manufacturing contributes to the taste and aroma of green tea [7]. Widely targeted metabolomic analysis revealed that the manufacturing of green tea, especially fixing, had an influence on the evolution of the non-volatile and volatile metabolites. Further analysis indicated that amino acids and lipids played a key role in the formation of volatile compounds [8]. Most non-volatile and volatile metabolites varied notably in different manufacturing processes, and the transformation of metabolites was the dominant trend during green tea processing [6]. During green tea manufacturing, especially in the fixation stage, significant lipidomic variations were observed, which potentially contribute to the color and aroma quality of tea [9]. All lipid degradation products, such as (E,E)-2,4-heptadienal, showed the highest concentrations in the fresh tea leaves but significantly lower concentrations in the final green tea [10]. Except for cis-3-hexenyl hexanoate, the concentrations of most aroma compounds decreased after fixation during the Xinyang Maojian (XYM) green tea manufacturing [11]. In China, green tea has the longest production history and an excellent quality. There are many world famous green teas, such as West Lake Longjing tea, XYMJ, Huangshan Maofeng, etc. The XYMJ green tea is one of the top ten most popular teas in China, which originates from Xinyang, Henan province, China [12]. With a production history of more than 2300 years and its excellent quality, the regional public brand value of XYMJ green tea has risen to 7.572 billion Yuan (RMB) in the year of 2022 and ranked third after West Lake Longjing tea and Pu'er tea. The manufacturing techniques of XYMJ green tea are traditional manual processing, the common manual-mechanical processing (the combination of manual and mechanical), and continuous mechanical processing [13]. The output of XYMJ green tea manufactured manually and mechanically accounts for the majority. A few studies have focused on the volatile compounds of XYMJ green tea [14; 15] and the key odorants responsible for the XYMJ green tea have been identified [16; 17]. To get a deeper insight into the effect of the single manufacturing process on the XYMJ green tea aroma formation, the key odorants and their dynamic changes during manufacturing processes from tea shoots to drying must be elucidated. Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) has been widely applied to determine volatile compounds in teas [18; 19; 20]. Thus, the aim of the present study was to investigate the key odorants in XYMJ green tea and their dynamic changes during the manufacturing processes using HS-SPME combined with GC-MS.