Untargeted metabolomics analysis based on HS-SPME-GC-MS and UPLC-Q-TOF/MS reveals the contribution of stem to the flavor of Cyclocarya paliurus herbal extract
Liang Lü, Yuchen Liu, Yuxin Liu, Siyi Gan, Xuejin Mao, Yuanxing Wang
Abstract
The herbal tea made from the leaves and stems of Cyclocarya paliurus is thought to be more flavorful than those made from the leaves only. However, evidence supporting this view is not available yet. 53 VOCs and 54 non-VOCs were identified via HS-SPME-GC-MS and UPLC-Q-TOF/MS, respectively, which were found to vary dramatically in three groups of samples (combination of stems and leaves, separated leaves, and separated stems). 11 VOCs and 18 non-VOCs potential markers are responsible for the change of metabolic effects through the biosynthesis of flavonoids, the synthesis of terpenoids, and the oxidation of fatty acids and carotenoids. In response, the stems were effective to enhance fatty odors, the initial astringency and bitterness and the aftertaste of sweetness of the leaves. Stems are conducive to increasing total phenolic content, total flavonoid content and antioxidant capacity of Cyclocarya paliurus herbal extract because of the increase in polyphenols. In addition, the stems have the potential to be used as raw materials for nerolidol and polyphenols extraction. This study has been the first to determine the contribution of stem to the flavor of Cyclocarya paliurus herbal tea and these results provide the theoretical basis for making Cyclocarya paliurus herbal tea with stems.