Interactions between Iron, Phenolic Compounds, Emulsifiers, and pH in Omega-3-Enriched Oil-in-Water Emulsions

Abstract

The behavior of antioxidants in emulsions is influenced by several factors such as pH and emulsifier type. This study aimed to evaluate the interaction between selected food emulsifiers, phenolic compounds, iron, and pH and their effect on the oxidative stability of n-3 polyunsaturated lipids in a 10% oil-in-water emulsion. The emulsifiers tested were Tween 80 and Citrem, and the phenolic compounds were naringenin, rutin, caffeic acid, and coumaric acid. Lipid oxidation was evaluated at all levels, that is, formation of radicals (ESR), hydroperoxides (PV), and secondary volatile oxidation products. When iron was present, the pH was crucial for the formation of lipid oxidation products. At pH 3 some phenolic compounds, especially caffeic acid, reduced Fe(3+) to Fe(2+), and Fe(2+) increased lipid oxidation at this pH compared to pH 6. Among the evaluated phenols, caffeic acid had the most significant effects, as caffeic acid was found to be prooxidative irrespective of pH, emulsifier type, and presence of iron, although the degrees of lipid oxidation were different at the different experimental conditions. The other evaluated phenols were prooxidative at pH 3 in Citrem-stabilized emulsions and had no significant effect at pH 6 in Citrem- or Tween-stabilized emulsions on the basis of the formation of volatiles. The results indicated that phenol-iron complexes/nanoparticles were formed at pH 6.

The antioxidative effect of lipophilized rutin and dihydrocaffeic acid in fish oil enriched milk

“…In more complex systems such as real food the antioxidant behaviour might be influenced by interaction with other components present in the emulsions, e.g. emulsifier and iron [15,18]. However, on the basis of studies in simple o/w emulsions we hypothesize that lipophilization of phenolics will increase their antioxidant efficacy in emulsified food enriched with n-3 PUFAs.…”

“…Moreover, recent experiments with phenolic compounds and two different emulsifiers in simple o/w emulsion have shown interaction of the antioxidants with emulsifier and iron [18]. The phenolic compounds investigated were caffeic acid, coumaric acid, naringenin and rutin, which were evaluated for interactions with Citrem and Tween with or without iron present.…”

Effect of Synthetic Emulsifier and Natural Biosurfactant on Feed Process and Quality of Pelletized Feed in Broiler Diet

“…Slow increased rate of peroxide formation in the diets after 14 days could be explained due to the inclusion of antioxidant in the poultry diet, which inhibits the reaction between antioxidant and free radicals that slow down the auto-oxidation or natural formation of peroxides from deteriorating (Gutteridge & Halliwell, 2010). The antioxidants could be partitioning into different phases of emulsion, either in oil phase, water phase or interface between these 2 phases with it´s respective efficacy to affect the oxidation rate (Sorensen et al, 2008).…”

Effect of oxygen availability and pH on the furan concentration formed during thermal preservation of plant-based foods

“…In real food 385 systems, the complexity is further increased, because the pH might have additional, indirect effects on 386 the furan formation through interactions with proteins (unfolding and/or reaction availability) (Cui et al 387 2013; Makinen et al 2016), metal ions (solubility and pro-oxidant properties) (Sorensen et al 2008) or 388 even the structure of the matrix (Fraeye et al 2007; Thongkaew et al 2015). The complexity of the 389 matrix makes it virtually impossible to provide a comprehensive explanation for the effects of pH on the 390 course of a reaction with multiple precursors, such as the furan formation.…”