###### Abstract  
Two plant-based emulsifiers, soybean lecithin and pea protein isolate, were studied for their emulsifying and encapsulating capacities of an antimicrobial molecule, _trans_-cinnamaldehyde (TC), at two different pH values, three and seven, and after drying with two different techniques, spray-drying and freeze-drying. To characterize the obtained capsules, various physicochemical tests were conducted to examine particle size, encapsulation efficiency, thermal and moisture stability, and powder morphology. The spray-dried (SD) and freeze-dried (FD) powders had an average particle size of 8.35 \(\upmu\)m and 144.49 \(\upmu\)m, respectively. The SD powders showed similar encapsulation efficiency (EE) for soybean lecithin and pea protein isolate with an average value of 95.69%. On the other hand, the FD powders had lower EE compared to SD powders, with an average of 58.01% for lecithin-containing powders and 83.93% for pea-protein-containing powders. However, the water content of FD powders (2.83%) was lower than that of SD powders (4.72%). The powders prepared at pH 3 showed better thermal stability. Morphological analysis showed spherical particles for SD powders and irregular shapes for FD powders. Nanoemulsions as well as dried powders showed interesting antimicrobial activities against _Escherichia coli_ and _Listeria imocua_, confirming their potential use as natural preservatives in foods. microencapsulation; nanoemulsion; _trans_-cinnamaldehyde; spray-drying; freeze-drying +
Footnote †: journal: Medical  
_trans_-cinnamaldehyde (TC) (trans-3-phenyl-2-propenal) is generally the major component in the extracted oil (60-75% of the total oil) and demonstrates good antimicrobial activity against pathogenic microorganisms [9]. _trans_-Cinnamaldehyde emulsions applied to real food systems such as watermelon juice showed significant growth inhibition of _Salmonella typhimurium_ and _Staphylococcus aureus_[10]. Certain factors must be considered in designing an appropriate encapsulation technique. Appropriate encapsulating agents, temperature, and drying methods are the most important factors for the encapsulation process [11]. Wall material is one of the main factors in the design of an encapsulation system. Maltodextrin is a hydrolyzed starch produced through the partial hydrolysis of starch with acid or enzymes. It is commonly used as a wall material in the microencapsulation of food ingredients. It is a substance with neutral aroma and taste that protects bioactive molecules against oxidation [12]. Low viscosity at high solids concentrations and relatively low cost are the other advantages of maltodextrin that make it a good choice to carry EOs. However, maltodextrin possesses a low emulsifying capacity and marginal retention of volatiles; that is why an emulsifier is needed when this wall material is used to encapsulate oily compounds. Soybean lecithin is a natural amphiphilic molecule that is a mixture of phospholipid derivatives and has recently received much attention as a potential natural emulsifier [13]. Lecithin has both hydrophilic and lipophilic properties, and its hydrophobic part could adsorb to the surface of oil droplets, while its hydrophilic heads tend to interact with water to promote dispersion [14]. Therefore, lecithin can improve the dispersion of the oil phase in water and create a stable emulsion [15; 16]. Furthermore, the use of pea protein as an emulsifier has been previously investigated as an attractive seed storage protein source for emulsifying applications due to its nutritional value, good functional properties, and non-allergic nature. In addition, there is evidence that pea protein can be used to produce stable emulsions [17]. To obtain dry microcapsules, the two most appropriate methods to preserve bioactive compounds are spray-drying and freeze-drying. Processing the emulsions into powders increases their stability and their ease of storage and expands their range of applications [18].