Abstract: In this work, 102 polyphenols and 16 triterpenic acids in ripe pears of 36 cultivars were analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with multiple reaction monitoring (MRM) mode, changes in the major components were investigated in comparison with data from our previous research on young fruits. It was found that pear fruits were rich in polyphenols and triterpenoids, among which, chlorogenic acid, quinic acid and arbutin were the primary polyphenols and ursolic acid was the predominant triterpenoid. The contents of most of these compounds were significantly reduced in ripe pears compared with young pears. Generally, 12 phenolic acid compounds such as quinic acid and chlorogenic acid, eight phenolic glycosides such as arbutin, five flavonoid compounds such as rutin and isorhamnetin-3-O-rutinoside, five flavan-3-ols such as catechin and epicatechin, and 10 triterpenic acids, such as betulinic acid, oleanolic acid and ursolic acid were ubiquitously detected in all cultivars and tentatively identified as the characteristic polyphenolic and triterpenoid constituents. Furthermore, the results of principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) showed that there was no significant difference among various pear cultivars and Pyrus ussuriensis Maxim cultivars exhibited strong species specificity. This study provides reference for further improving the pear quality evaluation system and for cultivar selection for various functional products in the future.

Key words: pear; polyphenols; flavonoids; triterpenic acids; ultra-high performance liquid chromatography-tandem mass spectrometry