## 3 Results and Discussion
### Preliminary Results
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sensory Properties**} & \multicolumn{2}{c}{**Fish Burger**} & \multicolumn{2}{c}{**Formulations**} & \\ \cline{3-6}  & & **Types** & & & \\ \hline \multirow{3}{*}{**Taste**} & & Control burger & 0.5\% _Spirulina_ & 1\% _Spirulina_ & 1.5\% _Spirulina_ \\  & & & fish burger & fish burger & fish burger \\ \hline \multirow{3}{*}{**After-taste**} & CB & 4.42 \(\pm\) 0.05 & 4.48 \(\pm\) 0.145 & 4.26 \(\pm\) 0.179 & 3.98 \(\pm\) 0.034 b f g \\ \cline{2-6}  & BB & 4.12 \(\pm\) 0.53 & 4.03 \(\pm\) 0.42 & 3.98 \(\pm\) 0.296 & 3.02 \(\pm\) 0.203 c e h \\ \hline \multirow{3}{*}{**After-taste**} & CB & 4.35 \(\pm\) 0.296 & 4.13 \(\pm\) 0.014 & 4.11 \(\pm\) 0.015 & 3.99 \(\pm\) 0.020 a  \\ \cline{2-6}  & BB & 4.08 \(\pm\) 0.251 & 4.10 \(\pm\) 0.428 & 4.07 \(\pm\) 0.381 & 3.39 \(\pm\) 0.307 a d g \\ \hline \multirow{3}{*}{**Odor**} & CB & 3.99 \(\pm\) 0.021 & 4.03 \(\pm\) 0.024 & 4.04 \(\pm\) 0.050 & 4.02 \(\pm\) 0.017 \\ \cline{2-6}  & BB & 4.01 \(\pm\) 0.283 & 4.00 \(\pm\) 0.261 & 4.01 \(\pm\) 0.312 & 4.05 \(\pm\) 0.311 \\ \hline \multirow{3}{*}{**Color**} & CB & 4.26 \(\pm\) 0.08 & 4.29 \(\pm\) 0.06 & 4.15 \(\pm\) 0.07 & 3.91 \(\pm\) 0.08 c f h \\ \cline{2-6}  & BB & 4.01 \(\pm\) 0.432 & 4.02 \(\pm\) 0.419 & 4.02 \(\pm\) 0.521 & 3.88 \(\pm\) 0.489 \\ \hline \multirow{3}{*}{**Mouth-texture**} & CB & 4.03 \(\pm\) 0.090 & 4.09 \(\pm\) 0.060 & 4.24 \(\pm\) 0.050 b d  & 4.17 \(\pm\) 0.022 a  \\ \cline{2-6}  & BB & 3.98 \(\pm\) 0.123 & 4.09 \(\pm\) 0.327 & 4.02 \(\pm\) 0.222 & 4.01 \(\pm\) 0.284 \\ \hline \multirow{3}{*}{**Overall-acceptability**} & CB & 4.12 \(\pm\) 0.032 & 4.12 \(\pm\) 0.020 & 4.13 \(\pm\) 0.034 & 4.03 \(\pm\) 0.023 b e h \\ \cline{2-6}  & BB & 4.12 \(\pm\) 0.156 & 4.11 \(\pm\) 0.238 & 4.08 \(\pm\) 0.145 & 3.80 \(\pm\) 0.05 a d g \\ \hline \hline \end{tabular}
\begin{tabular}{c} CB: carp burgers; BB: barbel burgers; Control vs. fortified burgers (0.5%, 1% and 1.5%): a \(p<0.05\); b \(p<0.01\); c \(p<0.001\); c \(p<0.001\); c \(p<0.001\); c \(p\) \(<0.001\); c \(p\) \(<0.001\); c \(p\) \(<0.001\); c \(p\) \(<0.001\). \\ \end{tabular}
\end{table} 
Table 1: Mean scores of tasting panelists (n = 30) for sensory properties of control and fortified burgers with different percentage (0.5, 1 and 1.5%) of _Spirulina_. concentration is the threshold level which has no significant effects on the sensory quality of the fish products; however, panel members were still satisfied with fish burgers containing 1% added _Spirulina_. Thus, carp and barbel burgers fortified with 0.5 and 1% of _Spirulina_ were chosen for further analyses to assess their physicochemical properties. The _Spirulina_ incorporation into fish burger composition had no significant effect on pH values (Table 2). Furthermore, the addition of _Spirulina_ (for any concentration) did not modify (\(p>0.05\)) the protein and fat contents (Table 2) for the two types of burgers. These contents were confirmed qualitatively with FTIR analysis (Figure 1A,B). The strong absorption in the region of 3200 cm\({}^{-1}\) corresponds to the hydroxyl (O-H) stretching vibration of proteins and residual water. The strong absorption in the region of 3000 and 2800 cm\({}^{-1}\) corresponds to the stretching of NH\({}_{2}\) groups, which reflects the high protein content in burger samples. The protein spectrum was characterized by the presence of absorption peaks at 1624 and 1522 cm\({}^{-1}\) attributed to the NH and C=O groups of amides I (1590-1650 cm\({}^{-1}\)) and the stretching of NH groups and asymmetric N=O groups of amide II (1500-1560 cm\({}^{-1}\)) [34]. The lipid spectrum was characterized by the presence of absorption peaks at 2922, 2852 and 1742 cm\({}^{-1}\) attributed to the stretching of Vas(CH\({}_{2}\)), Vs(CH\({}_{2}\)) and V(C=O), respectively, while the absorption peak at 1377 cm\({}^{-1}\) mainly showed the C-O stretching vibrations of carboxylic acids [34]. The absorption peaks found between 950 and 1200 cm\({}^{-1}\) represent carbohydrates [17].