## 3 Results and Discussion
### Muffin Characterization  
The influence of oil replacement by protein-based emulsion on the quality of muffins was established by assessing the physical properties of the muffins. Oil replacement by protein-based emulsion resulted in a significant increase of the protein and ash contents (\(p<0.05\)) and significantly affected (\(p<0.05\)) the height of the samples (Table 3). Our results are in line with the observations from previous studies reporting the height-reducing effect of partial oil replacement in muffin formulations with cocoa fiber [7], resistant dextrins obtained from wheat or maize starch [34], or cellulose ether emulsions [18]. Due to the higher amount of water used in the batter preparation when replacing the oil, the moisture content of the emulsion-based muffin samples was significantly higher (\(p<0.05\)) compared with the control (Table 3). Among all investigated muffin samples, those prepared with soy proteins-based emulsion exhibited the lowest weight loss during baking, whereas no significant changes were noticed between muffins prepared with lupin or yeast protein emulsions and the control. These results indicate that the emulsion-based muffins have high water-holding capacity, and from an economic standpoint, the production process is advantageous. The characteristics of the pores of the four types of muffins (Figure 5) considered in the study were determined through image analysis and the results are presented in Table 4. The porosity-related characteristic provides indication of the ability of the batter to retain the CO\({}_{2}\) released by baking powder during heating. As one can see in Figure 5, the pore size and homogeneity of the pore structure varied with the muffin samples. The average pore size was significantly higher in the case of the muffin samples prepared with emulsions (\(p<0.05\)). On the other hand, the control muffin sample had a higher number of uniformly distributed smaller pores (Figure 5). Considering that the same processing conditions were applied for preparing the batters and muffin samples, the observed differences could be attributed to the lower viscosity of the samples prepared with emulsions as the result of the higher amount of water in respect to the binding ability of the dry mixture. No important \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Muffin** & **Weight Loss during** & **Height, mm** & **Moisture, g/100 g** & **Protein, g/100 g d.w.** & **AgN, g/100 g d.w.** \\ \hline M & 7.43 \(\pm\) 0.86 \({}^{\mathrm{a}\mathrm{b}}\) & 4.68 \(\pm\) 0.08 \({}^{\mathrm{a}}\) & 21.71 \(\pm\) 0.24 \({}^{\mathrm{b}}\) & 8.31 \(\pm\) 0.10 \({}^{\mathrm{b}}\) & 1.21 \(\pm\) 0.02 \({}^{\mathrm{c}}\) \\ M1 & 6.81 \(\pm\) 0.29 \({}^{\mathrm{b}}\) & 4.46 \(\pm\) 0.05 \({}^{\mathrm{b}}\) & 26.00 \(\pm\) 0.54 \({}^{\mathrm{a}}\) & 9.31 \(\pm\) 0.07 \({}^{\mathrm{a}}\) & 1.29 \(\pm\) 0.04 \({}^{\mathrm{b}c}\) \\ M2 & 8.84 \(\pm\) 0.53 \({}^{\mathrm{a}}\) & 4.42 \(\pm\) 0.08 \({}^{\mathrm{b}}\) & 25.05 \(\pm\) 0.97 \({}^{\mathrm{a}}\) & 9.38 \(\pm\) 0.04 \({}^{\mathrm{a}}\) & 1.34 \(\pm\) 0.03 \({}^{\mathrm{a}b}\) \\ M3 & 8.32 \(\pm\) 0.50 \({}^{\mathrm{a,b}}\) & 4.54 \(\pm\) 0.09 \({}^{\mathrm{a,b}}\) & 25.97 \(\pm\) 0.98 \({}^{\mathrm{a}}\) & 9.45 \(\pm\) 0.09 \({}^{\mathrm{a}}\) & 1.40 \(\pm\) 0.04 \({}^{\mathrm{a}}\) \\ \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 3: Quality 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). differences were noticed between the investigated samples in terms of the cell-total area ratio (Table 4). The crumb cell structure exerts a major influence on how the texture and freshness of the product is perceived [20].