## 3 Results and Discussion
### Analysis of Berries
Another difference can be observed in the analysis of strawberries which contain the highest concentration level of AA (according to literature). The enzyme TYR catalyzes the oxidation of polyphenic compounds in berries only, therefore the lower TEAC values of strawberries at biosensor in comparison to reference method was found. This phenomenon corresponds to higher TEAC values obtained by DPPH assay compared to that of biosensor, because AA discolors the methanolic solution of DPPH radical, which tends to show a positive error. However, the developed biosensor could be applied in the direct determination of TPC as TEAC, in samples where phenolic compounds are major antioxidants. The comparison with other spectrophotometric assays such as ORAC, FRAP and TRAP intended for the determination of total antioxidant capacity in pulps of berries is shown in Table 2. Corresponding TEAC values in berries obtained at individual assays were found or calculated from data presented in literature [8; 30; 31; 32; 33]. The TYR biosensor provides a similar sensitivity to DPPH and TRAP assays. In comparison to ORAC assay, the sensitivity of biosensor is twice as low. From all of the analytical methods, the lowest ability to eliminate the negative influence of free radicals was observed for strawberries and oppositely the highest for cranberries. If we want to compare antioxidant capacities of individual berries, TYR biosensor provides similar information as DPPH, ORAC and TRAP assays in this sequence: cranberries \(>\) raspberries \(>\) blackberries \(>\) blueberries \(>\) strawberries. A correlation \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Berries**} & \multicolumn{2}{c}{**TEAC in Dry Matter (in Pulp) (mg\(\cdot\)100 g\({}^{-1}\))**} & \multirow{2}{*}{**AA in Pulp b [mg\(\cdot\)100 g\({}^{-1}\)]**} \\ \cline{2-3}  & **Tyrosinase Biosensor a ** & DPPH a Assay \\ \hline Strawberries & 1569 (133) & 6735 (570) & 59 \\ Blackberries & 2593 (337) & 3868 (503) & 30 \\ Raspberries & 5317 (793) & 5968 (890) & 32 \\ Blueberries & 1917 (270) & 4878 (687) & 14 \\ Cranberries & 6738 (935) & 8027 (1114) & 13 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: TEAC and AA content in various berries. coefficient \(R^{2}=0.8409\) was found during the comparison of the TYR biosensor with the DPPH assay in the analysis of TEAC in each berry's pulp. The better value of the correlation coefficient (\(R^{2}=0.9374\)) was obtained, when the TEAC of blackberries was excluded as an outlier. The same situation can be found for the comparison of TYR biosensor with TRAP assay (\(R^{2}=0.9622\)). Corresponding correlation graphs are shown in Figure 6. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Berries**} & \multicolumn{3}{c}{**TEAC (mg:100 g\({}^{-1}\))**} \\ \cline{2-4}  & **ORAC \({}^{\text{a}}\)** & **FRAP \({}^{\text{b}}\)** & **TRAP \({}^{\text{c}}\)** \\ \hline Strawberries & 1077 & 543 & 214 \\ Blackberries & 1478 & 1269 & 526 \\ Raspberries & 1268 & 994 & 262 \\ Blueberries & 1169 & 911 & 233 \\ Cranberries & 2275 & 1259 & 678 \\ \hline \hline \end{tabular} Data of TEAC content in berries are taken from Ref. \({}^{\text{a}}\)[6,8], \({}^{\text{b}}\)[30,31] and \({}^{\text{c}}\)[32].  
\end{table} 
Table 2: Survey of TEAC values in pulp of berries determined by other assays. Figure 6: Comparison of TYR biosensor with other analytical assays (**A**) DPPH, (**B**) ORAC, (**C**) FRAP and (**D**) TRAP for analysis of TEAC in pulps of strawberries (_Stra_), blackberries (_Blac_), raspberries (_Rasp_), blueberries (_Blue_) and cranberries (_Cran_). Moreover, it seems that ORAC and TRAP assays provide lower TEAC values than the TYR biosensor and two other spectrophotometric assays. An explanation could be found in different representations of phenolic substances in raspberries and cranberries, which probably contain a higher amount of phenolic substance, having catechol group in their chemical structures.