## 3 Results and Discussion
### Preliminary Results
Compared to control, _Spirulina_-fortified samples did not show a significant appearance of specific absorption peaks for the two types of fish burger (Figure 1A,B). \begin{table}
\begin{tabular}{c c c c c} \hline \multicolumn{2}{c}{**Physicochemical Characteristics**} & \multicolumn{2}{c}{**Fish Burger Types**} & \multicolumn{2}{c}{**Burger Formulations**} \\ \hline  & & Control burger & 0.5\% _Spirulina_ fish & 1\% _Spirulina_ fish \\  & & & burger & burger \\ \hline \multirow{2}{*}{pH} & CB & 7.21 \(\pm\) 0.07 & 7.16 \(\pm\) 0.01 & 7.17 \(\pm\) 0.01 \\ \cline{2-5}  & BB & 7.14 \(\pm\) 0.02 & 7.1 \(\pm\) 0.015 & 7.07 \(\pm\) 0.025 \\ \hline \multirow{2}{*}{**Water activity (a\({}_{w}\))**} & CB & 0.982 \(\pm\) 0.000 & 0.979 \(\pm\) 0.000 a  & 0.978 \(\pm\) 0.000 c  \\ \cline{2-5}  & BB & 0.982 \(\pm\) 0.001 & 0.974 \(\pm\) 0.000 c  & 0.969 \(\pm\) 0.001 c  \\ \hline \multirow{2}{*}{**Moisture (\% FW)**} & CB & 77.03 \(\pm\) 0.055 & 76.55 \(\pm\) 0.053 & 76.36 \(\pm\) 0.078 \\ \cline{2-5}  & BB & 77.57 \(\pm\) 0.32 & 77.17 \(\pm\) 0.072 a  & 77.00 \(\pm\) 0.046 b  \\ \hline \multirow{2}{*}{**Total solids (\% FW)**} & CB & 22.96 \(\pm\) 0.055 & 23.44 \(\pm\) 0.053 c  & 23.63 \(\pm\) 0.078 c  \\ \cline{2-5}  & BB & 22.43 \(\pm\) 0.32 & 22.82 \(\pm\) 0.072 & 23 \(\pm\) 0.046 a  \\ \hline \multirow{2}{*}{**Protein (\% DW)**} & CB & 79.66 \(\pm\) 0.119 & 79.50 \(\pm\) 0.019 & 79.20 \(\pm\) 0.096 \\ \cline{2-5}  & BB & 78.24 \(\pm\) 0.125 & 78.21 \(\pm\) 0.070 & 78.02 \(\pm\) 0.012 a  \\ \hline \multirow{2}{*}{**Fat (\% DW)**} & CB & 7.79 \(\pm\) 0.15 & 7.67 \(\pm\) 0.04 & 7.46 \(\pm\) 0.068 \\ \cline{2-5}  & BB & 8.33 \(\pm\) 0.085 & 8.25 \(\pm\) 0.095 & 8.24 \(\pm\) 0.010 \\ \hline \multirow{2}{*}{**Ash (\% DW)**} & CB & 11.12 \(\pm\) 0.105 & 11.18 \(\pm\) 0.013 & 11.69 \(\pm\) 0.046 c f  \\ \cline{2-5}  & BB & 11.53 \(\pm\) 0.03 & 11.56 \(\pm\) 0.315 & 11.84 \(\pm\) 0.155 c f  \\ \hline \multirow{2}{*}{**Total dietary fiber (g/100 g DW) \({}^{*}\)**} & CB & 0.32 \(\pm\) 0.024 & 0.5 \(\pm\) 0.075 c  & 0.76 \(\pm\) 0.024 c f  \\ \hline \multirow{2}{*}{CB: carp burger, BB: barbel burger; 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 \(p<0.001\); 0.5\% _Spirulina_ burgers vs. 1 and 1.5\% _Spirulina_ burgers: \({}^{4}\)\(p<0.05\); \(p<0.01\); \({}^{4}\)\(p<0.001\); T \(p<0. Nevertheless, total solids (TS), total dietary fibers and ash contents were found to be the highest in carp and barbel burgers fortified with _Spirulina_ (\(p<0.05\)) (Table 2). For carp formulations, TS of the control and fortified burgers with 0.5 and 1% of _Spirulina_ were 22.96, 23.44 and 23.63%, respectively. There was a significant difference in terms of TS between these 3 formulations (\(p<0.001\)) (Table 2). This increase was not significant between barbel formulations. Similarly, the dietary fiber values of all _Spirulina_-fortified burgers were significantly (\(p<0.01\)) increased when compared with that of control burgers. This was probably due to the high dietary fiber content of _Spirulina_. For the two types of fish burger, samples treated with 0.5% of _Spirulina_ significantly showed (\(p<0.001\)) lower values for dietary fibers in comparison to samples treated with 1% of _Spirulina_. The high dietary fiber content of fortified burgers might have played an important role in a reduced level of water activity (a\({}_{w}\)) compared with the control burgers [35]. In addition, _Spirulina_ increased the Ash content of carp and barbel burgers depending on microalga concentration (Table 2). These findings are consistent with previous results that indicated the richness of _Spirulina_ in minerals [21]. Variations in these physicochemical parameters, especially regarding the contents of dietary fibers, may affect certain other functional parameters such as water and oil holding capacities.