Antioxidant activity of alkyl gallates and glycosyl alkyl gallates in fish oil in water emulsions: Relevance of their surface active properties and of the type of emulsifier

Abstract

18The antioxidant activity of gallic acid and a series of alkyl gallates (C4 to C18) and glycosylated 19 alkyl gallates (C4 to C18) on fish oil-in-water emulsions was studied. Three types of emulsifiers, 20 lecithin, Tween-20 and sodium dodecyl sulphate (SDS) were tested. A nonlinear behaviour of the 21 antioxidant activity of alkyl gallates when increasing alkyl chain length was observed for emulsions 22 prepared with lecithin. Medium-size alkyl gallates (C6-C12) were the best antioxidants. In contrast, for 23 emulsions prepared with Tween-20, the antioxidants seem to follow the polar paradox. Glucosyl alkyl 24 gallates were shown previously to be better surfactants than alkyl gallates. Nevertheless, they exhibited 25 a worse antioxidant capacity than their corresponding alkyl gallates, in emulsions prepared with lecithin 26 or Tween-20, indicating the greater relevance of having three OH groups at the polar head in 27 comparison with having improved surfactant properties but just a di-ortho phenolic structure in the 28 antioxidant. 29 30Highlights 31 •Alkyl gallates exhibited good antioxidant (AO) activity in fish oil-in-water emulsions. 32 •The type of emulsifier affects their AO activity when increasing alkyl chain length. 33• Glucosyl alkyl gallates showed to be better surfactants than alkyl gallates. 34• Glucosyl alkyl gallates presented worse AO activity than alkyl gallates. 35 •Maintenance of the three OH groups at the antioxidant is crucial for AO activity. 36 37

Effects of gallic acid and its alkyl esters on lipid oxidation duringin vitrosimulated gastrointestinal digestion of fresh and fried oysters

“…To be specific, the antioxidant capacity gradually increases with chain length to a critical mass, thereafter, the antioxidant capacity decreases. A previous study showed that the antioxidant activity of GA and its alkyl esters changes nonlinearly with the increase of the alkyl chain length in the oil‐in‐water emulsion prepared with lecithin as the emulsifier, and the alkyl esters with medium chain length had the best antioxidant properties (González et al ., 2015). This phenomenon is called the ‘cut‐off’ effect (Laguerre et al ., 2017).…”

A comprehensive review on polarity, partitioning, and interactions of phenolic antioxidants at oil–water interface of food emulsions

“…It is important to note that gallic acid as a negatively charged antioxidant has shown different antioxidant mechanisms depending on the binding between the phenolic OH groups and the emulsifiers, for example, gallic acid acted as an antioxidant with lecithin and soy protein isolate (Asnaashari et al., 2014; Gonzalez et al., 2015), but as a prooxidant with Tween 20 and sodium dodecyl sulfate (Gonzalez et al., 2015). Zhao et al.…”

Encapsulation and stability of a phenolic-rich extract from mango peel within water-in-oil-in-water emulsions

“…These authors attributed this behavior to simultaneous transportation of dissolved molecules and water from W 1 to W 2 through the oil layer. Even when electrolytes, sugars or other osmotic pressure regulators are included in emulsions formulation, W 1 droplet expulsion might not be controlled, as some emulsifiers may enable or enhance transport phenomena (Garti, 1997 as it is suggested that antioxidants in food products should be located where the oxidation processes start, that is in emulsions, at the oil-water interface (González, Medina, Maldonado, Lucas, & Morales, 2015).…”