## 3 Results
### Swelling Experiments  
The ability of microcapsules to swell is shown in Figure 1. The value of this parameter was determined at five time points in an environment simulating gastric fluid (SGF), intestinal fluid (SIF), and colonic fluid (SCF). As can be seen, the swelling rate of microcapsules was the highest in SCF and the lowest in SGF. It was proven that Alg in an acidic buffer is converted into insoluble alginic acid [46]; hence, its significantly lower degree of swelling than in the SIF or SCF environment can be explained. In the acidic environment, only the microcapsules with a CE core retained their shape, and the swelling rate increased with time. In turn, for the microcapsules with a PE core, the degree of swelling increased with the reaction time up to 2 h and then slightly decreased. The same tendency was noted for the control microcapsules. This was most likely due to the fact that the higher content of polysaccharides in CE influenced the increasing degree of swelling of the microcapsules enriched with this extract and the preservation of their structure. This is also reflected in the analysis of the individual groups of microcapsules, where it can be seen that the Alg + Pect microcapsules, i.e., enriched with polysaccharides, are characterized by the highest degree of swelling. In turn, in PE microcapsules, a rapid release of anthocyanins could occur within the first two hours, which resulted in a reduced degree of swelling in an acidic environment in the subsequent hours of incubation. Such a relationship was suggested by [PERSON] et al. [47], who proved that the main factor for the rapid release of anthocyanins in SGF is the high compressive pressure, resulting in the termination of their release after an average of 2 h of incubation.  
In the SIF and SCF environment, all of the microcapsules swelled rapidly with incubation time. In general, the increase in the mass of microcapsules in water is due to their porous structure, which allows them to absorb fluids to fill the voids in the polymer network until the equilibrium state is reached [13]. However, both in the SIF and SCF environment for the control samples, a decrease in the swelling degree can be observed at 8 h of incubation, which was unnoticeable in the case of CE and PE microcapsules. These results can be attributed to the fact that the polyphenolic compounds of the encapsulated extracts could have a stabilizing effect on the used carriers in a neutral environment. Similar behavior of Alg-based microcapsules was observed in other works [10; 48]. For microcapsules of Alg and chitosan, [PERSON] et al. [10] showed that up to 3 h of reaction, the structure of the formed networks increased, thus the volume of the microcapsules increased. However, after this time, no COO\({}^{-}\) and NH\({}_{3}\)\({}^{+}\) functional groups remained free, which resulted in the disintegration of the microcapsules. In turn, [PERSON] et al. [48] noted the disintegration of Alg microcapsules in the SIF and SCF environment after 5 h of swelling. According to the authors, the disintegration of microspheres at high pH of the phosphate buffer results from the higher affinity of phosphate ions for calcium than for the Alg polymer, which ultimately leads to the disruption of the calcium alginate network and the disintegration of the microcapsules. Therefore, for the obtained microcapsules, no major differences in the degree of swelling were demonstrated depending on the encapsulation mixture used. However, the types of extracts used played an important role.