## 3 Results and Discussion
### Analysis of Differential VOCs in the Flesh of Eight Pear Varieties
Yali and Ruanerli had a higher content of Linalool, and its content in Yali showed a trend of increasing and then decreasing with the prolongation of shelf life, with the highest content detected at 3 d of shelf life, while Linalool content in Ruanerli fluctuated, reaching its maximum value of 0.08 mg/kg at 0 d of shelf life. It was found that that \(\alpha\)-Terpineol is associated with a floral and rose aroma [45]. Ruanerli had higher levels of \(\alpha\)-Terpineol compared to other varieties, with the highest level of 0.52 mg/kg detected at 14 d of shelf life. Jingbaili had a high concentration of trans-3-Hexenol on the day of harvest, which provides a green aroma odor to the fruit [46]. Furthermore, both Louis and Cure had higher levels of 1-Octen-3-ol, (E)-2-Octenal, (E)-2-Heptenal, and (E)-2-Decenal throughout the shelf life. Ketones. Ketones are the major fruits, sweet compounds in fruits [10]. Most ketones are produced via the degradation or decarboxylation pathway of carotenoids [47], with (E)-1-(2,6,6-Trimethyl-1,3-cyclohexadien-1-yl)-2-butten-1-one having a rose-like flavor and honey-like woody aroma [48]. (E)-1-(2,6,6-Trimethyl-1,3-cyclohexadien-1-yl)-2-butten-1-one was detected in all eight pear varieties, with higher levels in Louis, Cure and Ruanerli. 6-Methyl-5-heptene-2-one is reported to be a degradation product of lycopene [42] or \(\alpha\)-Farnesene [49] with green color and citrus flavor, which is commonly found in fruits such as apricot [42], lychee [44], prune plum [50] and apple [51]. It was found that Louis and Cure had higher concentrations of 6-Methyl-5-heptene-2-one; its content in Louis showed an increasing and then decreasing trend with the prolongation of shelf life, and the highest content of 0.17 mg/kg was detected at 3 d of shelf life, while its content in Cure gradually decreased. Hydrocarbons and others. At 14 d and 21 d of shelf life, Jingbaili and Nanguoli had high levels of (E,E)-\(\alpha\)-Farnesene, which were significantly higher than the rest of the shelf life. At the same time, Jingbaili also had high content of (Z,E)-\(\alpha\)-Farnesene. Other compounds were also detected in the eight pear varieties, such as trans-\(\alpha\),\(\alpha\),5-Trimethyl-5-etherylethhydro-2-furanmethanol, which was found to be higher in Ruanerli, and the content gradually decreased with the prolongation of shelf life. The results showed that the content of each VOC did not change much in crisp-flesh pears throughout the shelf life, while significant differences existed in soft-flesh pears. From a comparative analysis of the changes in the content of differential aroma substances in the eight pear varieties during shelf life, it was discovered that Yali and Hanhongli had green and sweet fragrance characteristics, and were best consumed within their respective shelf life of 0-3 d and 14 d. Korla pear exhibited green aroma characteristics and was best consumed within a shelf life of approximately 14 d. Nanguoli and Ruanerli had fruity aroma characteristics, with optimal consumption periods of 14-21 d and 3-7 d, respectively. In comparison, Jingbaili had a lighter fruity aroma, making it more suitable for consumption within a shelf life of 14 d. Louis and Cure exhibited floral and fruity aromas and were best for consumption after 21 d of shelf life.