## 4 Discussion  
According to the results of the above study, 1-hexanol and 2-ethyl- had the highest VOC content in LG01 and LG02. They have a sweet taste and light floral fragrance, and they are also present in green teas and natto [33; 51]. LG01 pear syrup was made of Laiyang pear, which has a light aroma and sweet taste [52]. The key VOC of LG01 was Hexanoic acid and ethyl ester, which is sweet and fruity [31]. LG02 was made of Korla pear, a White Pear variety, which is a specialty of Xinjiang, China. Originating from Xinjiang, China, where it has been cultivated for more than 1300 years, it has garnered the favor of both domestic and international consumers. Its distinct qualities, including a unique fragrance, juiciness, exceptional sweetness, and a particularly special aroma, have contributed to its widespread appeal [53]. The main ingredient of LG02 was a scent of grease, grass, and apple [31], and the key VOC was Hexanal. At the same time, hexanal was identified as a distinctive aroma component of Korla pear, indicating that the choice of raw materials significantly influences the VOCs present in pear syrup [54]. Furfural was the most abundant VOC in pear syrups from LG03 to LG09. It was widely present in tea, virgin olive oil volatility, and chixiang aroma-type liquor, and it is mainly bready, brown, sweet smell [29; 30; 31]. The key VOC of LG03, LG04, LG06, LG07, LG08, and LG09 was 1-Octen-3-one, among which LG03 was made of Xuehua pear, which has a single fruit weight of about 400g and rich juice and is often processed into dried fruits and canned products [55]. LG04 was made by Laiyang Cili, which is abundant in Laiyang City, Shandong Province. LG06 was made for Dangshan Suli, which is rich in Dangshan County, Anhui Province, China, and it is a geographical landmark pear product. LG07 was made by Dato Wuming pear and LG08 was made by Yali. Yali is abundant in Hebei Province, China, and is the main pear variety for export. It has a wide cultivated area and an annual output of about 2.6 million tons [56]. LG09 was made by [PERSON] in _Pyrus ussuriensis_ Maxim., which is rich in aroma, juicy, and soft after ripening and is a geographical symbol product in Liaoning Province, China. The key VOC of LG05 was Butanoic acid and methyl ester, and it has the odor of apple and cheese aromas [46] and was made from red pear. Undecane was the highest content VOC in LG10, which mainly existed in the foliar of Hibiscus fragrans Roxburgh [57], but the key VOCs were 2-Furancarboxaldehyde and 5-methyl-, which had a caramel aroma [45]. LG10 was made by Ningling Suli, which is abundant in Ningling County, Henan Province, China. The single fruit weight can reach 800-1000 g or more. When ripe, Ningling Suli is crisp and juicy and sweet and delicious. It was evident from the above analysis that the VOCs with the highest concentrations in pear syrups were not the key VOCs, which contrasts with [PERSON]'s findings [58]. Similar to research on soy sauce and strong aroma-type liquors, 2-Pentanol had the highest concentration but an odor activity value (OAV) of less than 1, while Ethyl hexanoate emerged as the most significant aromatic compound. This result aligns with the research carried out by [PERSON] et al. on soy sauce and strong aroma-type liquors, where 2-Pentanol had the highest content but OAV < 1 and Ethyl hexanoate was identified as the key VOC [58]. The raw materials used in pear syrup products on the market mainly consist of White Pear varieties, which are known for their crisp and juicy texture, as well as large single fruit weight. Among these, only LG09 was made by Nanguoli from the _Pyrus ussuriensis_ Maxim. due to its strong aroma and softness after ripening. Numerous researchers have discovered that Nanguoli contains nearly 100 VOCs [24], which is a key factor contributing to the abundance of processed products made by Nanguoli. The VOCs in fruits undergo changes at each stage of processing, and employing low-temperature processing techniques can largely preserve the inherent VOCs of the fruit.