## 3 Results and Discussion
### Mayonnaise Characterization
#### 3.2.2 Particle Size Analysis  
The particle size in the samples increased when the oil concentration decreased and was significantly higher than the commercial product (\(p<0.05\)) (Figure 2). All samples with 30% oil (A, D, and D') demonstrated a mean particle size in a range of 6-9 um; however, the presence of protein showed a slight reduction in particle size (6-7 um). In samples with lower oil content (22.5%), there was an increase in the particle size for A, B, C, D, E, and F (\(\sim\)10 um), while the systems with SPC (D', E,' and F') showed the twice size compared to the samples with 30% oil. In the case of the mayonnaies with the lowest content of oil (15%), D', E,' and F' showed smaller particle sizes (12 um) in comparison to the rest of the samples where the particles increased up to 30 um. Two possible mechanisms for this increase in particle size could occur. First, A, B, and C behavior could be due to the absence of a second emulsifier to help reduce the interfacial tension and reach smaller droplet sizes in emulsions [44]. In the case of D, E, and F, the SPI could contribute to a larger droplet size because the mayonnaise pH is close to this protein's isoelectric point (4-4.5). Hence, when the net charge is near or equal to zero (at the isoelectric point of the protein) leads to poor emulsifying activity and the generation of larger droplet size [45].  
Figure 2: Mean particle size (color bars) and span (gray bars) of the low-fat mayonnaies. A, B, C = sodium alginate low fat mayonnaise with 30, 22.5 and 15% oil. D, E, F = low fat mayonnaies with 30, 22.5 and 15% oil and soybean protein isolate. D’, E’, F’ = low fat mayonnaises with 30, 22.5 and 15% oil and spirulina protein concentrate. The different superscript letter indicates a significant difference (\(p<0.05\)).  
Our products showed larger particle sizes than related studies of low-fat mayonnaies. For example, [PERSON] et al. [46] developed mayonnaies with microparticulate Whey Protein Isolate (M-WPI), and the systems had approximately 2 \(\upmu\)m in diameter. The difference in the particle size could be because the M-WPI have a tiny particle size (-8 \(\upmu\)m), contributing to reducing the lipid droplets size in their products [46]. Nevertheless, the particle size determined in the samples with more than 22.5% oil showed comparable results to a previous report of low-fat mayonnaise (2-12 \(\upmu\)m) elaborated with modified starches [7].  
The span measurement indicates the width of the particle size distribution. Higher span values indicate more heterogeneous particle sizes within the system. The lowest span values (Figure 2) were found for the commercial low-fat mayonnaise and C (-0.9). In contrast, the rest of the samples showed values of 1.1-1.6, and the highest span (span = 2.7) was recorded in F'. The particle size distribution (Figure 3) in commercial mayonnaise and the samples with 22.5 and 30% oil (A, B, D, E, D', and E') was monomodal; on the contrary, the mayonnaises with 15% oil content (C, F, and F') showed a bimodal or multimodal distribution. Usually, systems with high viscosity and homogeneous particle size distribution (monomodal) have been related to better stability. In contrast, multimodal distributions are usually observed in low viscosity and unstable systems [47]. In our low-fat mayonnaies, only the latter behavior was detected (higher viscosity for monomodal systems), and even though the particle size distribution (multimodal) could induce instability, the presence of the sodium alginate probably helped to prevent the oil droplet movement and their further coalescence in the products [10].  
Figure 3: Particle size distribution of different mayonnaies. (**A**) Sodium alginate low-fat mayonnaies (A, B, C = 30, 22.5, 15% oil, respectively). (**B**) Low-fat mayonnaies with soy protein isolate (D, E, F = 30, 22.5, 15% oil, respectively). (**C**) Low-fat mayonnaises with spirulina protein concentrate (D’, E’, F’ = 30, 22.5, 15 oil%, respectively). (**D**) Commercial low-fat mayonnaise.