## 3 Results
### Technological and Chemical Properties of Bread
#### 3.3.1 Bread Colour and Volume  
Figure 3 illustrates that bread containing microalgae had a distinctive dark green colour in both the crumbs and crust.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Crust**} & \multicolumn{2}{c}{**Crumb**} \\ \cline{2-6}  & **L*** & **a*** & **b*** & **L*** & **a*** & **b*** \\ \hline Control & 63.26 \(\pm\) 2.31 \({}^{\text{a}}\) & 7.90 \(\pm\) 1.88 \({}^{\text{a}}\) & 32.23 \(\pm\) 2.52 \({}^{\text{a}}\) & 63.76 \(\pm\) 3.28 \({}^{\text{a}}\) & \(-\)1.05 \(\pm\) 0.26 \({}^{\text{b}}\) & 17.70 \(\pm\) 0.84 \({}^{\text{c}}\) \\ Cv & 32.79 \(\pm\) 1.78 \({}^{\text{c}}\) & 0.24 \(\pm\) 0.19 \({}^{\text{b}}\) & 18.21 \(\pm\) 1.45 \({}^{\text{c}}\) & 31.01 \(\pm\) 2.32 \({}^{\text{b}}\) & \(-\)4.32 \(\pm\) 0.23 \({}^{\text{c}}\) & 25.77 \(\pm\) 1.04 \({}^{\text{b}}\) \\ Pt & 39.63 \(\pm\) 1.30 \({}^{\text{b}}\) & \(-\)1.51 \(\pm\) 0.72 \({}^{\text{c}}\) & 22.95 \(\pm\) 1.97 \({}^{\text{b}}\) & 29.63 \(\pm\) 1.65 \({}^{\text{b}}\) & 0.67 \(\pm\) 0.15 \({}^{\text{a}}\) & 27.50 \(\pm\) 1.43 \({}^{\text{a}}\) \\ Tc & 38.70 \(\pm\) 2.40 \({}^{\text{b}}\) & 0.40 \(\pm\) 0.70 \({}^{\text{b}}\) & 22.98 \(\pm\) 2.00 \({}^{\text{b}}\) & 31.87 \(\pm\) 1.88 \({}^{\text{b}}\) & \(-\)6.46 \(\pm\) 0.92 \({}^{\text{d}}\) & 28.83 \(\pm\) 1.88 \({}^{\text{a}}\) \\ \hline \hline \end{tabular}
\end{table}
Table 4: Colour parameters (CIELAB system) of bread crumb and crust. Control: without microalgae; _Chlorella vulgaris_ (Cv), _Phaodactylum tricornutum_ (Pt), and _Tetraselmis chuii_ (Tc). Different letters in the same parameter show significant differences (\(p<\) 0.05, Tukey test).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Firmness**} & \multirow{2}{*}{**Cohesiveness**} & \multirow{2}{*}{**Elasticity**} & \multicolumn{2}{c}{**Volume (cm*)**} & \multirow{2}{*}{**Moisture (\%)**} & \multirow{2}{*}{**a\({}_{\text{w}}\)**} \\ \cline{2-2} \cline{6-6} Control & 1.80 \(\pm\) 0.36 \({}^{\text{b}}\) & 0.76 \(\pm\) 0.03 \({}^{\text{a}}\) & 0.99 \(\pm\) 0.02 \({}^{\text{a}}\) & 437.5 \(\pm\) 46.30 \({}^{\text{a}}\  
Notably, the crust colour closely corresponds with the crumb. The results in Table 4 revealed significant differences (\(p<0.05\)) in the L*, a*, and b* values between bread with microalgae and the control bread. Specifically, _C. vulgaris_ had the darkest crust colour and an L* value of 32.79, which was significantly different from _T. chuii_ (38.7) and _P. tricornutum_ (39.63). Bread containing _P. tricornutum_ displayed a more prominent green hue, as indicated by a negative a* value for the crust, while the crumb tended towards redness, characterised by a positive a* value. In all samples, both the crust and crumb were predominantly characterised by a yellow hue, as evidenced by positive b* values. Notably, the crust and crumb of _C. vulgaris_ displayed slightly less in degree yellow (b* = 18.2 and b* = 25.8, respectively). The green colour in microalgae-enriched bread is attributed to chlorophylls and carotenoid pigments. Its intensity varies with microalgae levels, aligning with previous research [12].  
In this study, the bread volume results (Table 5) showed no significant difference between the control bread and the bread with _P. tricornutum_ and _T. chuii_. However, the bread with _C. vulgaris_ exhibited a significant reduction (\(p<0.05\)) of volume (22.7% decrease). Previous studies have reported variations in the bread volume when different percentages of microalgae were used. Notably, bread enriched with higher levels of up to 8% of _A. platensis_, _C. vulgaris_, _Microchloropysis gaditana_, and _T. chuii_ showed a substantial reduction in loaf volume, possibly reaching up to a 40% decrease compared to those with lower additions of 4% [10]. This reduction in volume can be attributed to the interference in the gluten matrix, resulting from the partial replacement of flour with microalgae [55].