###### Abstract  
The gallated catechin content in Wuyi Rock Tea is higher in the summer, leading to a more bitter and less desirable taste. Here, tannase, tyrosinase, and lactose were used to treat summer Rougui Wuyi Rock Tea extracts. The effects of single and combined enzymes on the taste of the tea extracts and their mechanisms of action were analyzed. Compared with the no-enzyme-treated sample, the sensory score results showed that tannase was the most effective, increasing the bitterness and astringency scores by 113.9% and 255.3%, respectively. Among the combined enzyme treatments, the samples treated with tannase and tyrosinase yielded the best sensory scores, with bitterness and astringency scores increasing by 141.2% and 289.0%, respectively. Data obtained using an electronic tongue confirmed the role of these enzymes, showing that, in addition to bitterness and astringency, enzyme treatment also influenced the bitterness aftertaste and astringency aftertaste, as well as its sourness and sweetness. Further product analysis revealed that tannase hydrolyzes the ester bonds on the gallacyl groups in gallated catechins, converting them to non-gallated catechins, while tyrosinase and lactose oxidize the phenolic hydroxyl groups on catechins to form o-quinone, leading to the production of theaflavins and improved tea quality. This study presents an effective approach to improving the quality of summer tea using biological enzymes. R ougui Wuyi Rock tea; tannase; catechins; theaflavins; tea cream; electronic tongue 2020 IEEE/RSJ Web  
(TFs) and thearubigins (TRs) [5]. Catechins such as EGCG, ECG, and EGC in fresh leaves can be oxidized to polyphenols, such as theaflavins and thearubigins, under the action of endogenous polyphenol oxidase [6]. Theaflavins and thearubigins improve human health by reducing the blood sugar levels, having antioxidant [7,8] and antibacterial properties [9], and regulating the blood lipid levels [10]. Biological enzymes have good functional characteristics, such as high specificity and high catalytic efficiency, and have attracted great attention due to their environment-friendly properties [11]. Tannase (EC 3.1.1.20, TAN), whose full name is tannin acyl hydrolase, can hydrolyze the ester bonds of tea compounds, such as gallic acid esters and hydrolysable tannins, leading to the production of gallic acid and a small amount of glucose [12]. Tannase has a crucial role in juice and beverage processing. [PERSON], [PERSON] et al. [13] found that treating grapefruit juice with tannase can effectively reduce its bittermess and improve its antioxidant properties. [PERSON], [PERSON] et al. [14] reported that tannase can reduce the amount of precipitate produced with calcium, magnesium, and other metal ions, as well as protein substances, due to the high tannin concentration in beer and beverages. Polyphenol oxidase also plays an important role in the degree of fermentation and oxidation in tea processing, significantly affecting the color of tea beverages [15,16]. Tyrosine (EC 1.14.18.1, TYR) can oxidize the o-hydroxyl group of phenolic substances to o-diphenyl, and then oxidize it to o-quinone. Lacase (EC 1.10.3.2, LAC), which also has polyphenol oxidase activity, leads to the formation of free radicals after oxidation, and quinone is formed after two such oxidation reactions occur. Lacase has broader substrate specificity than tyrosinase [17]. [PERSON] et al. found that tyrosinase from mushrooms can be effectively used for the synthesis of theaflavins [6]. Moreover, [PERSON], [PERSON] et al. showed that a co-immobilization system incorporating lacase can enhance the development and industrial application of theaflavins [18]. The use of biological enzymes to improve tea quality has become a tea research hot spot. The content of gallated catechins in green tea infusions treated with tannase is reduced, demonstrating the effective ability of tannase to degrade precipitates [19].