# Encapsulation of Fennel Essential Oil in Calcium Alginate Microbeads via Electrostatic Extrusion
###### Abstract  
Fennel essential oil (EO) is well known for its biological activities and wide potential for use in the food, cosmetic, and pharmaceutical industries, where the main challenge is to achieve higher stability of EO. This study aimed to evaluate the potential of electrostatic extrusion for encapsulation of fennel EO by examining the effects of alginate (1%, 1.5%, and 2%) and whey protein (0%, 0.75%, and 1.5%) concentrations and drying methods on the encapsulation efficiency, loading capacity, bead characteristics, and swelling behavior of the produced fennel EO microbeads. Results revealed that electrostatic extrusion proved to be effective for encapsulating fennel EO, with whey protein addition enhancing the examined characteristics of the obtained microbeads. Freeze-drying exhibited superior performance compared to air-drying. Optimal encapsulation efficiency (51.95%) and loading capacity (78.28%) were achieved by using 1.5% alginate and 0.75% whey protein, followed by freeze-drying. GC-MS analysis revealed no differences in the qualitative aspect of the encapsulated and initial EO, with the encapsulated EO retaining 58.95% of volatile compounds. This study highlighted the potential of electrostatic extrusion using alginate and whey protein as a promising technique for fennel EO encapsulation while also emphasizing the need for further exploration into varied carrier materials and process parameters to optimize the encapsulation process and enhance product quality. [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], E.  
industrial use; however, researchers proposed modifying the structural setup by employing a multi-needle arrangement for the encapsulation of bioactive compounds to overcome this issue [7]. The principle of this technique is based on the use of electrostatic forces to disrupt the liquid biopolymer filament at the tip of a nozzle and to form a charged stream of small droplets into a gelling bath, resulting in a microbead with EO encapsulated within a gel matrix [8]. The choice of wall material in this technique is limited to the use of gums (xanthan and gellan), which may be chosen due to their emulsifying and gel-forming properties, and the most commonly used is alginate [6]. Alginate is a linear anionic polysaccharide derived from brown seaweed composed of 1,4-glycosic bond-linked \(\alpha\)-L-galuronic acid and \(\beta\)-D-mannuronic acid residues, which has the ability to form hydrogels in the presence of divalent cations. Ca\({}^{2+}\) is the most commonly applied cation in gelling baths because of its non-toxic and biocompatible features [6; 9]. Other materials such as chitosan, gum arabic, inulin, collagen, whey protein isolate, soy protein isolate, gelatin, egg album, zein, and casein can be combined with alginate in order to enhance the properties of the obtained microbeads. Whey proteins are a valuable by-product from the dairy industry with excellent gelling properties, which mainly stem from the presence of \(\beta\)-lactoglobulin (globular protein of 162 amino acid residues containing two disulfide bridges and a free thiol group) and as such have potential to enhance the properties of alginate microbeads, namely, the swelling behavior directly proportional to release kinetics of the EO, which is highly relevant since the loss of volatile compounds is mass transfer-controlled [8; 9; 10]. In addition, combining whey protein with alginate may also ameliorate the loss of EO caused by the porous structure of alginate hydrogel and regulate the shrinkage of the beads during drying [9]. The dimensions and physicochemical properties of the acquired beads are a function of the complex interplay of various operational parameters, system properties, and characteristics of the polymer solution, as well as the drying process, which is challenging due to the volatile nature of the EOs. Therefore, optimization is critical for attaining high encapsulation efficiency, stability, and ideal release kinetics [8].