# Encapsulation of Fennel Essential Oil in Calcium Alginate Microbeads via Electrostatic Extrusion
## 3 Results and Discussion
### Encapsulation Efficiency and Loading Capacity  
Encapsulation efficiency can be considered the most important parameter in evaluating the success of the encapsulation process, as it shows how much of the initial EO was entrapped in the produced microbeads. Loading capacity is another important factor, as it reflects how much of the EO can be contained by the used carrier and is most often defined by the properties of the used carriers [15]. In the present study, the encapsulation efficiency varied notably between samples and ranged from 6.16. to 51.95% (Table 1), which was similar to the range (10.57-63.17%) reported during encapsulation of thyme, geraniol, and rosemary EOs entrapped in alginate microbeads by oil emulsion technique [22], but also lower than 80% reported by [PERSON] et al. [12] during the encapsulation of thyme EO by emulsification or 90% reported by [PERSON] et al. [23] during preparation of alginate microbeads from several different EOs. Loading capacity also varied notably with a range from 39.23 to 82.60% (Table 1), where most values were similar to values obtained during encapsulation of oregano EO (64.19-78.64%) [13] and thyme EO (\(\sim\)30-55%) [15] by ionic gelation but higher than 22-26% reported during encapsulation of several EOs [23,24]. As mentioned previously, loading capacity was generally affected by the applied carriers, which was also a case in the present study since drying type had no significant effect, as opposed to the significant effect of the combination of alginate and whey protein where 1% alginate with 1.5% of whey protein resulted in the highest loading capacity. At 1.5% alginate containing 0.75% whey protein, the loading capacity increased, while further addition of whey protein caused the decrease in loading capacity, likely due to the decrease in free volume within the polymer-protein matrix, which reduced the amount of oil which could be entrapped [23]. At 2% alginate, adding whey protein had no significant effect on loading capacity, possibly due to the higher density of the gel with fewer pores, which reduced the ability to retain whey proteins. Many factors can influence the encapsulation efficiency in alginate-based systems, and they include the preparation technique, parameters applied, used carriers, properties of the Eos, and the quantity of the EO used in an encapsulation process [15]. For example, EOs rich in aliphatic structure components facilitate the hydrogen bonding between the alginate and EO, while aromatic compounds hinder the hydrophilic interactions with alginate or other carriers used [22]. Also, different ratios of carriers result in more or less available groups that react with the EO, resulting in varying encapsulation efficiency. In the present study, statistical analysis showed that the content of alginate in the applied range had no significant influence on the encapsulation efficiency, and the same was observed for whey protein. Their combination, however, had a significant effect, and it can be observed from the results in Table 2 that a 1% alginate combination with 1.5% whey protein significantly improved the encapsulation efficiency, while at 2% alginate, no significant differences were observed when whey protein was added. The highest encapsulation efficiency was achieved at a combination of 1.5% alginate and 0.75% whey protein, which suggests that a balance was achieved between stability, allowing for the protection of the EO from degradation or release, and adequate fluidity and dispersion, which facilitated the encapsulation of the EO. Adding a higher concentration of whey protein might have resulted in hindering EO entrapment by complex formation between the amino acid residues of the whey protein and carboxylic groups of alginate chains [25].