# Tea Infusions as a Source of Phenolic Compounds in the Human Diet
## 3 Results and Discussion  
The infusions of the analyzed tea were found to be a very good source of phenolic compounds, the content of which, depending on the tea type and leaf extraction time, ranged from 46.9 to 202.9 mg/100 mL (Table 1). Many authors have determined the phenolic compounds in tea infusions at a similar level [4; 5; 32; 37]. Red tea infusions proved to be the best source of these components, as they contained, during each analyzed brewing time, larger amounts of phenolic compounds than the infusions obtained from the other teas (Table 1, Figure 1). These differences became particularly noticeable as the duration of leaf extraction with water increased, as evidenced by the fact that briefly prepared red tea infusions contained phenolics at levels almost twice as high as the infusions made from the other tea types, and after 20 min of contact between the leaves and water, these differences were more than four times greater. The high polyphenic content in red tea infusions was confirmed by [PERSON] et al. [16], who concluded that they contain phenolic compounds at levels up to 199.8 mg/100 mL (which confirms the values determined by the author of the current study for pu-erh tea infusions prepared for longer than 20 min). Many authors argue that the best source of polyphenols are unfermented green teas [5; 44; 45; 46], although depending on their origin and type of leaves, some contain lower levels of these compounds [9; 16; 47]. Figure 2 shows the classification of plant \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Tea Type**} & **Extraction** & **Total Phenolic** & \multicolumn{3}{c}{**Oxalates**} & \multicolumn{3}{c}{**Mineral Elements [ng/100 mL]**} \\ \cline{3-8}  & **Time [min]** & **Compounds** & **[mg/100 mL]** & **Ca** & **Na** & **Cu** & **Mn** \\ \hline \multirow{4}{*}{green} & 6 & 58.0 \(\pm\) 0.81 fg & 18.00 \(\pm\) 0.00 fg & 132.1 \(\pm\) 1.89 g & 44.83 \(\pm\) 0.04 c & 3.90 \(\pm\) 0.03 c & 370.8 \(\pm\) 0.03 c \\  & 10 & 73.9 \(\pm\) 1.57 de & 24.24 \(\pm\) 2.30 d & 144.1 \(\pm\) 2.14 f & 42.88 \(\pm\) 0.11 c & 4.10 \(\pm\) 0.04 c & 470.1 \(\pm\) 2.16 b \\  & 20 & 102.0 \(\pm\) 0.98 c & 26.96 \(\pm\) 1.77 b & 164.2 \(\pm\) 2.06 e & 42.10 \(\pm\) 0.16 c & 6.12 \(\pm\) 0.11 b & 560.2 \(\pm\) 2.46 a \\  & 30 & 82.0 \(\pm\) 2.30 d & 30.88 \(\pm\) 1.35 a & 179.3 \(\pm\) 1.99 d & 42.15 \(\pm\) 0.10 c & 5.86 \(\pm\) 0.22 b & 539.1 \(\pm\) 3.19 a \\ \hline \multirow{4}{*}{red (pu-erh)} & 6 & 97.2 \(\pm\) 2.26 c & 15.06 \(\pm\) 0.74 g & 250.3 \(\pm\) 245 c & 260.12 \(\pm\) 1.06 e & 2.40 \(\pm\) 0.03 f & 140.42 \(\pm\) 2.27 f \\  & 10 & 133.0 \(\pm\) 3.17 b & 21.80 \(\pm\) 0.24 d & 255.1 \(\pm\) 2.87 bc & 261.37 \(\pm\) 204 a & 3.09 \(\pm\) 0.02 c & 190.2 \(\pm\) 4.11 e \\  & 20 & 202.9 \(\pm\) 3.00 a & 29.05 \(\pm\) 0.14 ab & 262.2 \(\pm\) 2.88 b & 261.00 \(\pm\) 1.11 a & 2.30 \(\pm\) 0.04 d & 230.1 \(\pm\) 0.09 d \\  & 30 & 202.3 \(\pm\) 5.74 a & 28.71 \(\pm\) 0.64 ab & 282.2 \(\pm\) 1.66 a & 262.13 \(\pm\) 0.22 a & 2.60 \(\pm\) 0.07 e & 236.3 \(\pm\) 1.42 d \\ \hline \multirow{4}{*}{black} & 6 & 66.6 \(\pm\) 1.42 fg & 17.19 \(\pm\) 0.78 fg & 49.3 \(\pm\) 0.22 k & 61.12 \(\pm\) 1.70 b & 8.42 \(\pm\) 0.55 a & 172.4 \(\pm\) 3.14 e \\  & 10 & 52.9 \(\pm\) 4.41 gh & 17.54 \(\pm\) 0.74 fg & 55.7 \(\pm\) 0.67 f & 63.22 \(\pm\) 2.34 b & 4.14 \(\pm\) 0.21 c & 223.1 \(\pm\) 2.03 d \\ \cline{1-1}  & 20 & 49.7 \(\pm\) 1.18 gh & 18.50 \(\pm\) 0.90 f & 65.1 \(\pm\) 0.76 i & 64.11 \(\pm\) 0.66 b & 4.30 \(\pm\) 0.20 c & 240.1\(\pm\) 2.89 d \\ \cline{1-1}  & 30 & 46.9 \(\pm\) 0.98 h & 19.93 \(\pm\) 1.11 e & 78.1 \(\pm\) 0.11 h & 64.28 \(\pm\) 0.53 b & 5.40 \(\pm\) 0.04 b & 257.0 \(\pm\) 3.11 d \\ \hline \hline \end{tabular} a-values in columns denoted by the same letters are not statistically in the analyzed type of tea at \(p<0.05\); data are expressed as mean values \(\pm\) standard deviations (SDs) of three samples (n = 3). The significance of differences was determined using Duncan’s test.  
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