## 3 Results and Discussion
### Muffin Characterization
The firmness of the muffins was measured at 12 h after baking. Analyzing the results presented in Table 4, one can see that oil substitution by emulsion in the batter formulations resulted in a significant increase of firmness. Our results comply with the observations of [PERSON] et al. [18] who reported a significant hardness increase when using cellulose ether emulsions in the muffins formulation instead of oil. Color is an important attribute of food products which might influence the consumers' choice in a decisive manner. The color usually depends on the type and amount of ingredients used for the preparation of different foods, as well as on their interaction and transformation during processing. The difference in color (\(\Delta\)E) between the control sample and muffins prepared with different types of protein-based emulsions is presented in Table 5. For all emulsion-based muffin samples, the \(\Delta\)E fell within the 1.5-3.0 range, which, in agreement with [PERSON] et al. [35], suggests noticeable differences in respect to the sample prepared with sunflower oil. As all the samples exhibited similar a* values, the \(\Delta\)E variations are mainly due to brightness (L*) and yellow (b*) chromaticity. The color intensity (C*) varied significantly with the source of fats (\(p<0.05\)), being more vivid in the emulsion-based muffins (Table 5). \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Muffin Sample**} & \multicolumn{2}{c}{**Porosity Characteristics**} & \multirow{2}{*}{**Firmness, N**} \\ \cline{2-2} \cline{4-4}  & **Average Size (m\({}^{2}\)-10\({}^{-6}\))** & & \\ \hline M & 1.29 \(\pm\) 0.01 b* & 0.48 \(\pm\) 0.01 a & 5.00 \(\pm\) 0.11 b \\ M1 & 1.76 \(\pm\) 0.05 a & 0.47 \(\pm\) 0.01 a & 5.64 \(\pm\) 0.40 a,b \\ M2 & 1.74 \(\pm\) 0.08 a & 0.48 \(\pm\) 0.04 a & 5.86 \(\pm\) 0.33 a \\ M3 & 1.69 \(\pm\) 0.02 a & 0.53 \(\pm\) 0.04 a & 5.79 \(\pm\) 0.20 a \\ \hline \hline \end{tabular}  
* Significant differences among results on the same column, determined by ANOVA and Tukey post hoc test at \(p<0.05\), are shown by different superscript lowercase letters.  
\end{table} 
Table 4: Porosity and texture characteristics of the muffin samples prepared with different types of emulsion (M—control prepared with sunflower oil, M1—muffins prepared with soy protein-based emulsion, M2—muffins prepared with lupin protein-based emulsion, M3—muffins prepared with yeast protein-based emulsion). Images were captured using a Canon PowerShot G16 digital camera (Canon Inc., Tokyo, Japan). Figure 5: Structure of the crumb of muffin samples with different types of emulsion (M—control prepared with sunflower oil, M1—muffins prepared with soy protein-based emulsion, M2—muffins prepared with lupin protein-based emulsion, M3—muffins prepared with yeast protein-based emulsion). Images were captured using a Canon PowerShot G16 digital camera (Canon Inc., Tokyo, Japan). The scoring method was applied for the sensory analysis of the muffin samples and the sensory scores for the main attributes are shown in Table 6. Oil replacement by protein-based emulsions resulted in no significant differences in color, flavor, taste, and appearance of the muffin samples. In agreement with the results of the instrumental analysis, showing that among all investigated samples, those with lupin and yeast protein-based emulsions had the highest firmness values (Table 4), the textures of these muffins were rated with the lowest scores (Table 6). However, no important differences between control and emulsion-based muffins were observed in terms of overall quality.