## 1 Introduction  
As flavoring agents, essential oils are generally incorporated into beverage products in an emulsified form because of their poor water-solubility [1]. Essential oil emulsions are more prone to gravitational separation (creaming) than vegetable oil emulsions because the density contrast between essential oils and water is greater than that between vegetable oils and water [2]. Emulsified essential oils are also highly prone to droplet growth caused by Ostwald ripening [3]. Ostwald ripening occurs via the diffusion of oil molecules from smaller droplets to larger droplets through the aqueous solution that separates them [4]. This phenomenon does not usually cause destabilization of emulsified vegetable oils because of the extremely low water-solubility of long-chain triglycerides. Conversely, it promotes destabilization of emulsified essential oils because of the much higher water-solubilities of these oils [5]. The increase in droplet size caused by Ostwald ripening also increases their susceptibility to creaming and coalescence. Consequently, to confer long-term stability to emulsified essential oils, it is important to inhibit or prevent both creaming and Ostwald ripening. Creaming can be prevented by reducing the density gradient between the oil and aqueous phases, thereby extending the shelf life of the emulsion. In beverage applications, weighting agents are typically added to the oil phase of essential oil emulsions to increase its density and make it more similar to that of the surrounding aqueous phase, thereby reducing the driving force for gravitational separation [6]. According to previous studies, the rate of Ostwald ripening in emulsions is affected by the initial droplet size distribution, the water-solubility of the used oils, and the oil phase composition [1; 7]. The tendency for emulsified essential oils to undergo Ostwald ripening can be reduced by incorporating strongly hydrophobic oils into the oil phase prior to homogenization [8]. These strongly hydrophobic oils are usually referred to as ripening inhibitors and have a very low water-solubility. Ripening inhibitors slow down droplet growth due to an entropy of mixing effect that counter-balances the interfacial curvature effect that drives Ostwald ripening. As the water-soluble essential oils move from smaller to large droplets, their concentration in the small droplets decreases whereas their concentration in the large droplets increases. As a result, there is a concentration gradient, which generates an osmotic pressure, which favors the movement of essential oil molecules from the larger to the smaller oil droplets--a process known as compositional ripening. After a certain time, the Ostwald ripening and compositional ripening processes balance each other and droplet growth is inhibited. [PERSON] et al. [9] found that the molecular characteristics of the surfactants coating the oil droplets in emulsions affected the diffusion of oil molecules from the droplets. The surfactant type may impact molecular diffusion processes in emulsions by altering the interfacial tension, thickness, rigidity, or permeability. For instance, [PERSON] and [PERSON] [10] reported that sufficiently rigid interfacial coatings could inhibit Ostwald ripening by resisting droplet shrinkage and expansion. Similarly, it has been reported that multilayer-coatings formed by electrostatic deposition can inhibit Ostwald ripening, which was attributed to their increased rigidity [11; 12]. We therefore hypothesized that the surfactant type would impact the rate of Ostwald ripening in model beverage emulsions, and selection of an appropriate surfactant may be a useful tool for slowing down droplet growth through this process. In this study, we examined the combined effects of ripening inhibitor concentration on the stability of model beverage emulsions (emulsified orange oil) stabilized using poly (ethylene glycol) alkyl ether surfactants having various hydrophilic head sizes.