Oils may also contain natural or
added antioxidants such as tert-butylhydroquinone, butylated
hydroxytoluene, tocopherols, and flavonoids. Hydrophilic components,
including free radical scavenging antioxidants (ascorbic
acid, phenolics, peptides, or proteins) and chelators (EDTA,
citric acid, polyphosphates, and proteins) may be added to the
aqueous phase to reduce interactions with iron or reduce the
presence of radical species that could destroy carotenoids. The
pH of the environment may also be controlled by the formulation
of the aqueous phase, which may help to prevent
acid-initiated degradation as well as controlling the solubility
of aqueous components like iron that is known to degrade
carotenoids.