*2.1. Chemicals*

2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), gallic acid, and 1,1-diphenyl-2- picrylhydrazyl (DPPH) were purchased from Merck (Sigma Aldrich, Beijing, China). De Man Rogosa Sharpe (MRS) and M17 media were obtained from Thermo Fisher Biochemicals (Shanghai, China).

#### *2.2. Preparation of the Chinese Sweet Tea Extract*

Air-dried *Rubus suavissimus* S. Lee (Chinese sweet tea) leaves (local market, Nanning city, China) were extracted with boiling water (1:15 *w*/*v*) for 60 min, as previously described [3]. The boiled mixture was centrifuged at 5000× *g* for 15 min at room temperature and then filtered through Whatman filter paper no. 1. The final filtrate was then freeze-dried. The Chinese sweet tea extract powder was analyzed for the protein, fat, ash, and total solid contents, as previously described [18], while the carbohydrate content was calculated by the di fferences.

#### *2.3. High-Performance Liquid Chromatography (HPLC) Analysis of Phenolic Compounds*

The identification and quantification of the individual phenolic compounds were carried out using an Agilent-1260 HPLC (USA) equipped with a C18 column (Kinetex ® 5 μm EVO 100 × 4.6 mm, Phenomenex, Torrance, CA, USA) [19]. In brief, 5 g of Chinese sweet tea extract was dissolved in 50 mL of methanol and centrifuged at 6000× *g* for 10 min. After filtration (0.22 μm syringe filter, Minisart®, Sartorius Stedim Boitech, Beijing, China), 20 μL of the filtrate was injected and separated by isocratic elution of water with 0.2% phosphoric acid (*v*/*v*) (A; 96%), methanol (B; 2%), and acetonitrile (C; 4%) at a 0.7 mL/min flow rate. The phenolic compounds were monitored at 280 nm using a UV detector. The quantification of the phenolic compounds was calculated with external calibration through the data analysis system of the Agilent software. All the phenolic standards were provided by Merck (Sigma Aldrich, Beijing, China).

#### *2.4. Yogurt Manufacture*

Yogurt was produced according to the method of Abdel-Hamid et al. [14]. In brief, skimmed buffalo milk (Guangxi Buffalo Research Institute Farm, Nanning, China) was heat-treated at 90 ◦C for 10 min and then rapidly cooled to 43 ◦C. The heat-treated milk was inoculated with yogur<sup>t</sup> culture (YO-MIX 300, Danisco, China), a mix of *Lactobacillus delbrueckii ssp. bulgaricus*, and *Streptococcus thermophilus,* according to the manual provided by the manufacturer. The cultured milk was divided into four equal parts: one part was used as a control treatment and the other three parts were incorporated with the Chinese sweet tea extract powder at concentrations of 0.25%, 0.5%, and 1% (*w*/*w*). Each milk portion was poured into plastic containers (120 mL) and incubated at 42 ◦C until the pH was reduced to 4.6. The yogur<sup>t</sup> treatments were kept at 4 ± 1 ◦C.

#### *2.5. Chemical Composition*

The carbohydrate, protein, and total solid contents of the cultured milk combined with the Chinese sweet tea extract powder were measured by a MilkoScan analyzer (F120, FOSS, Hillerød, Denmark). The pH values of the yogur<sup>t</sup> samples were monitored using a digital pH meter (Methrohm AG, Herisau, Switzerland).

#### *2.6. Bacterial Counts*

Bacterial counts of the yogur<sup>t</sup> samples were performed after 24 h of storage at 4 ◦C using the pour plate method [14]. *S. thermophilus* was grown on M17 agar, and the plates were aerobically incubated at 37 ◦C for 24 h. *L. bulgaricus* was enumerated on MRS agar (pH 5.4), and the plates were anaerobically incubated at 37 ◦C for 24 h. The results are presented as log colony-forming units per gram yogur<sup>t</sup> (CFU/g).

#### *2.7. Yogurt Supernatant*

The yogur<sup>t</sup> supernatant was separated by centrifugation at 22,000× *g* for 30 min at 4 ◦C, followed by filtration using a 0.45 μm syringe filter (Minisart®, Sartorius Stedim Boitech, Beijing, China). The filtrate of the yogur<sup>t</sup> samples was used to evaluate the total phenolic content and the biological activities—i.e., the antioxidant, anticancer, and antihypertensive activities.

#### *2.8. Total Phenolic Content (TPC)*

The TPC of the Chinese sweet tea extract powder and the yogur<sup>t</sup> samples was measured using the Folin–Ciocalteu assay [8]. Thirty microliters of the yogur<sup>t</sup> supernatant or the Chinese sweet tea extract powder (1 mg/mL in water) were pipetted into a 96-well plate, and then distilled water (120 μL) and Folin–Ciocalteu's phenol reagen<sup>t</sup> (30 μL) were added, respectively, to each well, followed by 30 μL of sodium carbonate (1N). The plates were incubated in the dark for 30 min at room temperature, and then the absorbance was read at 750 nm using a microplate reader (EPOCH, BioTek, Winooski, VT, USA). A standard curve was constructed using different concentrations of gallic acid. The results are expressed as the μg gallic acid equivalents (GAE) per milliliter.

#### *2.9. Antioxidant Activity*

ABTS and DPPH radical scavenging assays were used to evaluate the antioxidant activity of the yogur<sup>t</sup> samples according to Abdel-Hamid et al. [14]. In short, 50 μL of the yogur<sup>t</sup> supernatant was pipetted into a 96-well plate followed by ABTS+ solution (200 μL). The plate was then incubated in the dark for 30 min, and the absorbance was monitored at 405 nm using a microplate reader.

For the DPPH assay, DPPH reagen<sup>t</sup> (0.2 mM) was freshly prepared and added to the yogur<sup>t</sup> supernatant (1:1 *v*/*v*). After a 30 min reaction in the dark at 37 ◦C, the absorbance was measured at 517 nm.

#### *2.10. Anticancer Activity*

The anticancer activity of the yogur<sup>t</sup> samples was assessed against the Caco-2 carcinoma cell line (HTB-37; American Type Culture Collection, Manassas, VA, USA), and the cells were propagated according to Abdel-Hamid et al. [20]. Caco-2 cells were plated into 96-well plates (3000 cells/well) and incubated overnight at 37 ◦C under 5% CO2. The cells were then treated with 25 μL of the yogur<sup>t</sup> supernatant and grown again for 24 h. The viability of the treated cells was evaluated by the WST assay. The antiproliferative activity was calculated using the following equation:

$$\text{Antiprodéferative activity (\%)}=[1-(\text{A}-\text{B})/(\text{C}-\text{B})] \times 100,\tag{1}$$

where A is the absorbance of the cells in the presence of the yogur<sup>t</sup> supernatant, B is the background absorbance (non-cell control), and C is the absorbance of the control (cells with sterilized water instead of the yogur<sup>t</sup> supernatant).

#### *2.11. Antihypertensive Activity*

The antihypertensive activity of the Chinese sweet tea extract and the yogur<sup>t</sup> samples was investigated by measuring the angiotensin-converting enzyme (ACE) inhibitory activity. The spectrophotometric method was employed to evaluate the ACE inhibition by the Chinese sweet tea extract and the yogur<sup>t</sup> samples using the ACE Kit-WST (Dojindo laboratories, Shanghai, China) [20].

#### *2.12. Sensory Evaluation*

Samples of the yogur<sup>t</sup> with and without Chinese sweet tea extract were characterized organoleptically after 24 h of cold storage at 4 ± 1 ◦C by seven trained panelists (researchers at Guangxi University, Nanning, China) with an interest and experience in the sensory evaluation of fermented milk. A 9-point scale was used to evaluate the yogur<sup>t</sup> samples in terms of their appearance, aroma, texture, and overall acceptability, as described by Romeih et al. [21].

#### *2.13. Statistical Analysis*

Three independent experiments were performed in this study, and the results are presented as the mean ± standard deviation (SD). A one-way analysis of variance (ANOVA) was carried out with Statistix 8.1 (Analytical Software, Tallahassee, FL, USA) using Tukey's test for pairwise comparison. The correlation between variables was evaluated by the Pearson correlation test.

#### **3. Results and Discussion**

#### *3.1. Impact of the Chinese Sweet Tea Extract on the Chemical Composition of the Yogurt Samples*

The chemical characterization of the Chinese sweet tea extract powder is presented in Table 1. The Chinese sweet tea extract powder contained 94.22 ± 1% total solids, 6.4 ± 0.25% protein, and 80.18 ± 1.2% total carbohydrates. The chemical composition of the heat-treated milk with the Chinese sweet tea extract before fermentation was measured using the MilkoScan, and the results are presented in Table 2. The addition of the Chinese sweet tea extract had no significant e ffect (*p* > 0.05) on the protein content of the yogur<sup>t</sup> samples, whereas the total solid and total carbohydrate contents were significantly increased (*p* < 0.05) compared with the control yogur<sup>t</sup> sample. These results might be attributed to the high contents of carbohydrates and total solids in the Chinese sweet tea extract powder. It has been reported that the crude water extract of Chinese sweet tea contains 11% polysaccharides [2]. A similar trend was observed for the total carbohydrate and total solid contents in yogur<sup>t</sup> supplemented with *Siraitia grosvenorii* fruit, moringa, and *Gnaphalium a*ffi*ne* extracts [8,14,22].

**Table 1.** Characterization of the Chinese sweet tea extract.


Values are the mean of three replicates ± standard deviation. \* Total phenolic content presented as mg of gallic acid equivalents (GAE) per gram of Chinese sweet tea extract powder. ACE-I, angiotensin-converting enzyme-inhibition.



Results are the mean of three experiments ± standard deviation. Values in the same column with different superscript letters are significantly different (*p* < 0.05). \* Total phenolic content presented as μg gallic acid equivalents (GAE) per milliliter of yogur<sup>t</sup> supernatant.

Regarding the TPC, the Chinese sweet tea extract powder contained 21.54 ± 0.55 mg GAE/g (Table 1). The yogur<sup>t</sup> with the Chinese sweet tea extract had a significantly higher TPC content (*p* < 0.05) compared to the control yogur<sup>t</sup> sample, which gradually increased with an increase in the amount of Chinese sweet tea extract (Table 2). The highest TPC content (130.58 μg GAE/mL) was measured in the yogur<sup>t</sup> sample containing 1% Chinese sweet tea extract. These results are in agreemen<sup>t</sup> with those of Amirdivani and Baba [12], Gao et al. [22], Karaaslan et al. [7], and Zhang et al. [8], who found significantly increasing TPC contents in yogur<sup>t</sup> fortified with green tea, moringa, *Gnaphalium a*ffi*ne,* grape, and callus extracts. It should be noted that the TPC contents reported in these studies were lower than those detected in our study (130.58 μg GAE/mL).

#### *3.2. Identification and Quantification of Phenolic Compounds in the Chinese Sweet Tea Extract*

The phenolic compounds were determined using the HPLC assay, and the results are presented in Table 3. A total of 19 phenolic compounds were identified and quantified in the Chinese sweet tea extract powder, with concentrations ranging from 0.08 to 2.77 mg/g. Benzoic acid, quercetin, rutin, syringic acid, ellagic acid, and gallic acid were the most abundant phenolic compounds detected in the Chinese sweet tea extract. Indeed, Koh et al. [3] reported ellagic acid, rutin, and gallic acid as the major phenolic compounds of Chinese sweet tea, and they used the rubusoside content to evaluate the quality of the Chinese sweet tea. It has been reported that the concentrations of ellagic acid, rutin, and gallic acid in 14 Chinese sweet tea samples collected in different seasons ranged from 0.46% to 92%, 0.08% to 0.15%, and 0.1% to 0.16%, respectively [2]. More recently, Liu et al. [5] reported 14 new phenolic compounds in Chinese sweet tea leaves. In our study, seven new phenolic compounds were identified for the first time in Chinese sweet tea namely, *p*-coumaric acid, benzoic acid, *o*-coumaric acid, resveratrol, neringein, rosmarinic, and myricetin. These findings sugges<sup>t</sup> that the phenolic compound content varies according to the region and season of growth [2].


**Table 3.** Identified phenolic compounds in the Chinese sweet tea extract.

Values are the mean of three replicates ± standard deviation.

#### *3.3. pH and Bacterial Count*

The addition of the Chinese sweet tea extract increased the fermentation time from 5 h in the control yogur<sup>t</sup> sample to 6 h in the yogur<sup>t</sup> sample containing the 1% Chinese sweet extract. This was probably due to the antibacterial activity of the Chinese sweet tea components toward lactic acid bacteria, along with its acknowledged inhibition of pathogenic bacteria [13,23]. Additionally, Chinese sweet tea contains a high amount of benzoic acid, which is known to be an antimicrobial agen<sup>t</sup> (Table 3). Likewise, the fermentation time was not affected by the addition of green and black teas [10]. In contrast, it has been reported that the addition of moringa, *Mentha piperita*, *Anethum graveolens*, or *Ocimum basilicum* extracts to yogur<sup>t</sup> shortens the fermentation time due to the enhancement of the growth of yogur<sup>t</sup> cultures [8,15].

The pH values of the yogur<sup>t</sup> samples after 24 h of cold storage are presented in Table 4. The addition of the Chinese sweet tea extract had no significant effect (*p* > 0.05) on the pH values. In agreemen<sup>t</sup> with this finding, the use of different types of spices (i.e., cardamom, cinnamon, or nutmeg), moringa, and cinnamon and licorice herbals in the preparation of yogur<sup>t</sup> had no significant effect on the pH values compared with the relevant control yogur<sup>t</sup> [8,23,24].

**Table 4.** Viability of the yogur<sup>t</sup> cultures (log CFU/g) and pH values of the yogur<sup>t</sup> fortified with Chinese sweet tea extract.


Results are the mean of three experiments ± standard deviation. Values in the same column with different superscript letters are significantly different (*p* < 0.05).

The viability of the yogur<sup>t</sup> cultures of *S. thermophilus* and *L. bulgaricus* is presented in Table 4 as the log CFU/g yogurt. The viable cell counts of *L. bulgaricus* and *S. thermophilus* in the yogur<sup>t</sup> samples were 8.6–8.9 and 9.1–9.3 log CFU/g, respectively. The viable counts of *L. bulgaricus* and *S. thermophilus* in the yogur<sup>t</sup> samples are higher than the recommended dose to promote health benefits (>6 log CFU/g) [25]. Yogurt samples fortified with Chinese sweet tea had no significant influence (*p* > 0.05) on the viability of *L. bulgaricus* and *S. thermophilus.* A similar trend was reported for the addition of strawberries and green or black teas before yogur<sup>t</sup> fermentation [10,26]. Behrad et al. [23] reported that yogur<sup>t</sup> mixed with cinnamon and licorice herbals had lower counts of *L. bulgaricus* and *S. thermophilus* compared to the control plain yogurt. In contrast, the addition of Japanese and Malaysian green teas or moringa extract significantly improved the viability of *L. bulgaricus* and *S. thermophilus* in yogur<sup>t</sup> [8,12]. These findings demonstrate that the e ffects of the addition of extracts on the fermentation time, pH values, and culture viability of yogur<sup>t</sup> depend on the plant type and the phytochemical concentrations.

#### *3.4. Antioxidant Activity*

The antioxidant activities of the yogur<sup>t</sup> samples were measured by ABTS and DPPH assays, and the results are presented in Table 5. The antioxidant activity of the yogur<sup>t</sup> samples ranged between 14.2% and 74.83% for the DPPH assay and between 32.01% and 92.43% for the ABTS assay. The addition of Chinese sweet tea extract significantly increased (*p* < 0.05) the antioxidant activity as the amount of extract added increased. The yogur<sup>t</sup> sample containing 1% Chinese sweet tea extract showed the highest ABTS (92.43%) and DPPH (74.83%) values. A positive correlation was observed between the TPC and the antioxidant activity for the DPPH (*r* = 0.998) and ABTS (*r* = 0.993) assays. Shori et al. [27] reported a similar trend between the TPC and antioxidant activity of phytomix-3+ mangosteen (a mixture of *Lycium barbarum*, *Momordica grosvenori,* and *Psidium guajava* leaves) yogurt. The increase in the antioxidant activities of yogur<sup>t</sup> fortified with Chinese sweet tea extract could be due to the higher concentrations of phytochemicals (i.e., phenols, flavonoids, and rubusoside) in Chinese sweet tea [2]. Our results are in agreemen<sup>t</sup> with those of Amirdivani and Baba [12] and Najgebauer-Lejko et al. [11], who found significantly higher antioxidant activities in yogur<sup>t</sup> supplemented with Japanese green tea, Malaysian green tea, green tea, or Pu-erh tea compared to the control yogurt. Furthermore, the addition of moringa, *Mentha piperita*, *Anethum graveolens*, *Ocimum basilicum*, spice oleoresins (i.e., cardamom, cinnamon, and nutmeg), grape seed, and cinnamon and licorice herbal extracts significantly increases the antioxidant activity of yogur<sup>t</sup> [8,9,13,15,23,24]. These authors concluded that the increase in antioxidant activities is a result of the concentrations of phenolic compounds in the plant extracts.


**Table 5.** Antioxidant activity of the yogur<sup>t</sup> fortified with Chinese sweet tea extract.

Results are the mean of three experiments ± standard deviation. Values in the same column with different superscript letters are significantly different (*p* < 0.05).

It is worth noting that the antioxidant activities of the yogur<sup>t</sup> samples containing Chinese sweet tea extract measured by the DPPH (29.8–74.8%) and ABTS (49.4–92.4%) assays were higher than the antioxidant activities of the yogur<sup>t</sup> produced by the above-mentioned studies. This may be attributed to the di fferences in the phytochemical types and their concentrations.

#### *3.5. Anticancer Activity*

The anticancer activity of the yogur<sup>t</sup> samples was examined by measuring the ability of the yogur<sup>t</sup> supernatant to inhibit the proliferation of the Caco-2 cell line, and the results are presented in Table 6. The Chinese sweet tea extract exhibited a 89.06% ± 3.7% anticancer activity at a concentration of 0.4 mg/mL (Table 1). The control yogur<sup>t</sup> sample also showed anticancer activity, which is most probably attributed to the presence of bioactive peptides. A similar finding was reported by Sah et al. [17]. Although the addition of 0.25% Chinese sweet tea extract had no significant impact (*p* > 0.05) on the anticancer activity levels compared to the control yogur<sup>t</sup> sample, yogur<sup>t</sup> samples containing 0.5% and 1% Chinese sweet tea extract exhibited significantly higher (*p* < 0.05) anticancer activity than that of the control yogur<sup>t</sup> sample (Table 5). Moreover, the supernatant of the yogur<sup>t</sup> sample containing 1% Chinese sweet tea extract showed the highest anticancer activity and inhibited the growth of the Caco-2 cell by 67.46%. It is worth noting that the anticancer activity was positively correlated *(r* = 0.961) with the TPC contents of the yogurts. This finding is probably attributed to the phytochemical content of the Chinese sweet tea extract, including phenolic compounds and rubusoside [2,3]. George Thompson et al. [28] reported that rubusoside, the main component in Chinese sweet tea (5% in dry leaves), inhibits the glucose (GLUT1) and fructose (GLUT5) transporters associated with cancer and diabetes. In addition, quercetin, rutin, and ellagic acid, which are among the major phenolic compounds in Chinese sweet tea, show anticancer activity against colon carcinoma cells, as described by Hashemzaei et al. [29] and Papoutsi et al. [30]. In accordance with our results, Sah et al. [17] reported the potential anticancer activity of probiotic yogur<sup>t</sup> supplemented with pineapple peel powder against HT29 colon cancer cells compared to the control. These authors attributed this finding to the enhanced extent of proteolysis and, consequently, the resultant bioactive peptides released by the addition of pineapple peel powder to the yogurt.


**Table 6.** Antiproliferative and ACE-I activities of the yogur<sup>t</sup> fortified with Chinese sweet tea extract.

Results are the mean of three experiments ± standard deviation. Values in the same column with different superscript letters are significantly different (*p* < 0.05).

#### *3.6. Antihypertensive Activity*

The antihypertensive activity was evaluated using the ACE inhibition method, as ACE is a key factor in the conversion of angiotensin I to angiotensin II, which raises blood pressure [31]. Chinese sweet tea extract exhibited a 86.85% ± 2.1% ACE inhibitory activity at 0.4 mg/mL (Table 1). The ACE inhibitory activity of the yogur<sup>t</sup> samples is shown in Table 6. The yogur<sup>t</sup> samples without the addition of Chinese sweet tea also showed an ACE inhibitory activity, which may due to the presence of bioactive peptides with ACE inhibitory activities already known to be present in yogur<sup>t</sup> products. In this context, Abdel-Hamid et al. [14] and Amirdivani and Baba [15] also reported ACE inhibitory activity for their control yogurts. As can be seen in Table 6, the addition of Chinese sweet tea extract significantly enhanced (*p* < 0.05) the ACE inhibitory activity of the yogur<sup>t</sup> samples. The ACE inhibitory activity was increased by increasing the amount of Chinese sweet tea extract added, where the yogur<sup>t</sup> sample containing 1% Chinese sweet tea extract showed the highest value (82.03%). This finding could be due to the bioactive compounds in the Chinese sweet tea extract. It should be noted that quercetin, rutin, and gallic acid, the major phenolic compounds in the Chinese sweet tea extract, exhibit antihypertensive activity both in vitro and in vivo, as reported by Balasuriya and Rupasinghe [32], Kang et al. [33], and Shaw et al. [34]. In addition, the ACE inhibitory activity of the yogur<sup>t</sup> samples was positively correlated with the TPC (*r* = 0.994). It has been reported that Chinese sweet tea exhibits antihypertensive activity, which can be attributed to its phytochemical content [35]. These results are in accordance with those reported by Liu and Finley [36], who concluded that phytochemicals reduce blood pressure. Furthermore, *Chrysophyllum cainito* fruit extract, rich in polyphenols, shows ACE inhibitory activity by chelating Zn2<sup>+</sup> ions (enzyme cofactor) [31]. Amirdivani and Baba [15] reported that yogur<sup>t</sup> fortified with herbal water extracts (i.e., *Mentha piperita, Anethum graveolens,* and *Ocimum basilicum*) exhibited a higher ACE inhibitory activity compared to the control yogurt. Moreover, the addition of Raftiline

HP ® has been shown to significantly improve the ACE inhibitory activity compared to plain yogur<sup>t</sup> [16]. These authors attributed the increase in ACE inhibitory activity after the addition Raftiline HP ® or herbal water extracts to the higher degree of proteolysis of the fortified yogurts, resulting in bioactive peptides with ACE inhibitory activity. However, Amirdivani and Baba [15] reported that the water extract of *Mentha piperita, Anethum graveolens,* or *Ocimum basilicum* itself had no ACE inhibitory activity. Interestingly, the obtained ACE inhibitory activity values of yogurts prepared with Chinese sweet tea extracts were higher than those reported by Amirdivani and Baba [15] and Ramchandran and Shah [16].

It should be noted that the Chinese sweet tea extract had no e ffect on either the viability of the yogur<sup>t</sup> culture (Table 4) or the degree of hydrolysis (data not shown). However, the Chinese sweet tea extract exhibited potential anticancer and antihypertensive activities (Table 1). Accordingly, the biological activities (i.e., antioxidant, antihypertensive, and anticancer activities) of the yogur<sup>t</sup> samples containing Chinese sweet tea extract are most probably attributed to the phytochemicals present in Chinese sweet tea.

#### *3.7. Sensory Evaluation*

Sensory characteristics are very important for assessing the consumer acceptability of yogur<sup>t</sup> products and to confirm that the additives have no negative impacts on the organoleptic parameters of said yogur<sup>t</sup> products. The sensory evaluation of the yogur<sup>t</sup> samples fortified with Chinese sweet tea extract is shown in Table 7. The yogur<sup>t</sup> samples containing Chinese sweet tea extract received almost similar appearance scores as the control yogur<sup>t</sup> sample (*p* > 0.05). The addition of the Chinese sweet tea extract significantly increased (*p* < 0.05) the texture score. Furthermore, the addition of Chinese sweet tea significantly enhanced (*p* < 0.05) the aroma of the yogur<sup>t</sup> samples compared to the control yogur<sup>t</sup> sample, which could be due to the sweet taste of rubusoside. In particular, the yogur<sup>t</sup> sample containing 1% Chinese sweet tea extract received the lowest perceived aroma score (*p* < 0.05) compared to the samples containing 0.25% and 0.5% Chinese sweet tea extract and the control yogur<sup>t</sup> sample. This finding may be attributed to the bitter aftertaste of rubusoside and some phenolic compounds [2,3]. Similarly, the overall acceptability score of the yogur<sup>t</sup> samples containing 0.25% and 0.5% Chinese sweet extract was significantly higher (*p* < 0.05) than the control yogurt, while the yogur<sup>t</sup> sample containing 1% Chinese sweet tea extract received the lowest overall acceptability score. In this context, yogur<sup>t</sup> prepared with moringa extract at di fferent levels (i.e., 0.05%, 0.1%, and 0.2%) had a significantly lower sensory evaluation compared to the control yogur<sup>t</sup> [8]. The authors attributed these results to the better taste of moringa. The above results demonstrate that the yogur<sup>t</sup> samples with 0.5% Chinese sweet tea extract had the best sensory evaluation.

**Table 7.** Sensory evaluation of yogur<sup>t</sup> fortified with Chinese sweet tea extract.


Results are the mean of three experiments ± standard deviation. Values in the same column with different superscript letters are significantly different (*p* < 0.05).
