## 3 Results and Discussion
### Electronic Tongue Determination and Analysis of the Rock Tea Extract After the Enzyme Treatment  
The electronic tongue is a new analytical method based on a multi-sensor array, characterized by its high objectivity and interactive sensitivity. [30]. By simulating the human taste mechanism, it can identify samples that are difficult for the human senses to distinguish, thereby obtaining more objective and comprehensive sample information and having improved efficiency and accuracy. It is widely used in various fields of the food industry, such as tea, wine, and milk production [31]. Here, bitterness, astringency, sourness, saltness, umami, and sweetness sensors were used to collect data.  
Regarding the results obtained from the electronic tongue detection of the tea extracts, the properties of the enzyme-treated samples were significantly different (\(p<0.05\)). When the three enzymes were each individually applied to the tea extract, tannase had the greatest effect on the taste of the tea extract, with the sourness and sweetness increasing by 31.39% and 10.02%, respectively, while the bitterness, astringency, bitterness aftertaste, and astringency aftertaste decreased by 29.25%, 37.63%, 37.31%, and 62.53%, respectively. The umami and richness were also reduced by 23.56% and 25.71%, respectively. Tyrosine and lactose had similar effects on the taste of the tea extract, but their impact was much lower than that of tannase (Figure 4a). Among the samples treated with complex enzymes, the improvement effects of TAN-TYR, TAN-LAC, and TAN-TYR-LAC on the tea extract taste tended to be consistent, with the best effect being observed for TAN-TYR. This enzyme combination increased the sourness and sweetness by 34.70% and 7.72%, respectively. The bitterness, astringency, bitterness aftertaste, and astringency aftertaste decreased by 35.05%, 48.21%, 51.54%, and 69.92%, respectively. Umami and richness decreased by 21.94% and 26.67%, respectively. The effect of TAN-LAC and TAN-TYR-LAC on the reduction in bitterness and astringency was slightly lower than that of TAN-TYR (Figure 4b), likely due  
Figure 3: Sensory scores of the tea extracts for the different enzyme compound methods used. ck indicates the sample that has not been treated with the enzyme; TAN-TYR indicates tannase 2.4 U/mL + tyrosinase 4 U/mL; TAN-LAC indicates tannase 2.4 U/mL + lactose 4 U/mL; TYR-LAC indicates tyrosinase 4 U/mL + lactose 4 U/mL. TAN-TYR-LAC indicates tannase 2.4 U/mL + tyrosinase 4 U/mL + lactose 4 U/mL. The error bar represents the standard error of the mean, and by the LSD test, the average of different lowercase letters indicates a significant difference (\(p<0.05\)).  
to the action of increase. The precursor oxidation products of thearubigins are theaflavins, theacitrins, and theanaphtoquinones, among others. When laccase is added to the tea extracts, due to its broader substrate specificity, the content of thearubigins is likely to increase; moreover, thearubigins are also one of the main contributors to the bitterness of tea [17]. The increase in sourness and sweetness is probably related to a change in the contents of gallic acid and glucose. When tannase acts on the ester bonds to break them, gallic acid and a small amount of glucose are produced [32]. The results of the electronic tongue test were generally consistent with the sensory score ones.