关键词: 日照白茶；感官品质；生化成分；香气成分；顶空固相微萃取-气相色谱-质谱联用仪

Abstract: To investigate the current quality status of Rizhao white tea in Shandong province, the biochemical quality indicators of 18 Rizhao white tea samples were determined and their sensory quality was evaluated. Meanwhile, their key aroma compounds were analyzed using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS). Three Fujian white tea samples were used as controls. The sensory evaluation results showed that Rizhao white tea was grayish-green in color and exhibited intact leaves with prominent bud cores. Fujian white tea had a pure and refreshing tip aroma and tasted mellow. Rizhao white tea had a delicate, sweet aroma with floral notes, and its taste was fresh, sweet and mellow. Both tea infusions had a light yellow, apricot-yellow or orange-yellow color and were bright and clear, and the infused tea leaves were soft to the touch. The soluble sugar and total flavonoid contents of most Rizhao white tea samples were higher than those of Fujian white tea, the average content of amino acid was slightly lower than that of Fujian white tea, the tea polyphenol content was slightly lower than that of Fuding white tea, while the differences in water extract and caffeine contents were not significant. A total of 172 aroma components were detected in the 21 white tea samples. Using the cutoff of variable importance in projection (VIP) score > 1 with a P value < 0.05, 9 differential volatile substances were selected between Rizhao and Fujian white tea made from one bud with one or two leaves, and 10 differential volatile substances were selected between Rizhao and Fujian tea samples made from single leaves (single leaves with stems). Based on relative odor activity values (ROAV), linalool, geraniol, benzyl alcohol, phenylethanol, leaf alcohol, methyl salicylate, trans-β-ionone, trans linalool oxide (furan), benzaldehyde, and 2-pentyl furan were identified as key aroma compounds in Rizhao white tea. Moreover, the ROAV of the aroma compounds geraniol, methyl salicylate, trans-β-ionone, and 2-pentyl furan were higher than those of Fujian white tea, indicating that Rizhao white tea was richer in key aroma compounds.

Key words: Rizhao white tea; sensory quality; biochemical components; aroma components; headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry