Effects of Surfactant Volume Fraction on the Antioxidant Efficiency and on The Interfacial Concentrations of Octyl and Tetradecyl p-Coumarates in Corn Oil-in-Water Emulsions

Abstract

Surfactants have been used for decades in the food industry for the preparation of lipid-based emulsified food stuffs. They play two main roles in the emulsification processes: first they decrease the interfacial tension between the oil and water, facilitating droplet deformation and rupture; second, they reduce droplet coalescence by forming steric barriers. However, addition of surfactants to binary oil-water mixtures also brings up the formation of three-dimensional interfacial layers, surrounding each emulsion droplet, that significantly alter chemical reactivity. This is the case, for instance, in the inhibition reaction between antioxidants and the lipid radicals formed in the course of the spontaneous oxidation reaction of unsaturated lipids, which are commonly employed in the preparation of food-grade emulsions. The rate of the inhibition reaction depends on the effective concentrations of antioxidants, which are mostly controlled by the amount of surfactant employed in the preparation of the emulsion. In this work, we analyze the effects of the surfactant Tween 20 on the oxidative stability and on the effective concentrations of two model antioxidants derived from cinnamic acid, determining their interfacial concentrations in the intact emulsions to avoid disrupting the existing equilibria and biasing results. For this purpose, a recently developed methodology was employed, and experimental results were interpreted on the grounds of a pseudophase kinetic model.

Optimizing Fucoidan Encapsulation in a W1/O/W2 Double Emulsion through an Ultrasound-Assisted Process and Response Surface Methodology

“…The addition of surfactant to emulsions can suppress the oxidation of the oil, leading to a lower POV in addition to fucoidan with an inbuilt antioxidant agent as we reported in the literature section. In this argument in particular, the surfactant Tween 20 has been shown to suppress the oxidation of canola oil in O/W emulsions in a dose-dependent manner as reported by Costa et al The use of surfactants in emulsions can also alter the chemical reactivity of the emulsion droplets, which affects the rate of oxidation. Because of this, the quantity of emulsifiers, such as Tween 20, in W/O/W double emulsions can help manage the POV of sunflower oil by stopping oxidation reactions.…”

Unexpected Antioxidant Efficiency of Chlorogenic Acid Phenolipids in Fish Oil-in-Water Nanoemulsions: An Example of How Relatively Low Interfacial Concentrations Can Make Antioxidants to Be Inefficient

“…Our tentative explanation for the observed experimental behavior is based on the following rationale [39]. The oxidative stability of an emulsified system depends on the balance of several factors, including the concentration of AOs and of radicals in the interfacial region, where the inhibition reaction mainly takes place [21,25,28,31,40,41]. If the interfacial concentrations of antioxidants are low, antioxidants may not be able to remove peroxyl radicals at sufficient speed to halt the propagation step.…”