## 3 Results and Discussion
### Protein Concentration and Degree of Hydrolysis of Microcapsules during In Vitro Digestion  
Figure 6 shows the results for protein concentration and degree of hydrolysis for the gastric and intestinal digestion phases for the WPI-CMC and WPI-SA systems. Regarding the results for protein concentration shown in Figure 6, a decrease was observed over hydrolysis time for both the gastric and intestinal phases. The protein concentration found at the beginning of the gastric phase could be caused by the presence of free non-coacervated protein, because the coacervation efficiency for both systems was approximately 90% and 78% for WPI-CMC and WPI-SA, respectively [10]. This indicates that a small amount or protein and polysaccharide did not interact during coacervation, leaving some protein in the solution, which during the drying process was deposited on the surface of the coacervated dry capsules and was then suspended into the SGF during digestion. Figure 6a shows that the concentration of protein at the beginning of the gastric phase is significantly higher for the WPI-SA system, which is consistent with the lower coacervation efficiency for this system (higher amount of protein that did not coacervate with SA). Figure 5: Particle size distribution of coacervated microcapsules with (a) WPI-CMC and (b) WPI-SA systems at the beginning (0 min) and end (120 min) of intestinal digestion. Figure 6: Cont. The decrease in protein concentration during in vitro digestion has also been reported in a soy milk bioaccessibility study and was attributed to the enzymatic hydrolysis of the protein-structure-forming peptides [26], which could not be detected by the Bradford protein assay. This is because the blue dye Coomassiee Brilliant Blue G-250 (CBBG) has a low affinity for low-molecular-weight peptides (\(<\)3 kDa) [27; 28; 29; 30]. With respect to the degree of hydrolysis of the protein during the gastric phase, at the initial time (0 min), there were no detectable values for hydrolysis in either system of coacervation. At the end of this phase (120 min), a slight increase in the degree of hydrolysis was observed--up to 1.85% for the capsules prepared with WPI-CMC and 4.83% for the WPI-SA system, which indicated a limited action of pepsin. This slight increase may be explained by the hydrolysis of the free protein that remained on the surface of the capsule after coacervation, as was previously mentioned. Statistical analysis show that the degree of hydrolysis is significantly higher for the WPI-SA system, which is consistent with the higher protein concentration of the beginning of the gastric phase. For the intestinal digestion phase, the protein concentration and the hydrolysis percentage were determined at 0, 90, and 120 min. As shown in Figure 6b, for both systems of coacervation the protein concentration decreased with the digestion time, and at the same time there was an increase in the degree of hydrolysis, which was 1.85%, 16.69%, and 23.87% for the WPI-CMC system, and 4.83%, 16.91%, and 21.79% for the WPI-SA system, respectively. This indicated an effective action of the digestive enzymes on the exposed protein of the microcapsules. These results are in accordance with the reports of [PERSON] et al. [31] and [PERSON] et al. [32], who obtained a degree of hydrolysis from 5.5% to 24% for whey protein with different enzymes and hydrolysis conditions [31; 32; 33; 34]. Based on the degree of hydrolysis obtained in this work, these hydrolysates could be classified as extensive hydrolysates because they present a degree of hydrolysis higher than 10% [35]. From the above results, it can be concluded that the \"empty\" microcapsules, coacervated with both polysaccharides (CMC and SA), remained stable at 2.5 pH, because they maintained a low free protein concentration, very low degree of hydrolysis, and a particle size that was very similar to the coacervated powder from the beginning to the end in the gastric digestion.