Effects of selected herb extracts on iron-catalyzed lipid oxidation in soybean oil-in-water emulsion

Abstract

Effect of herb extracts on the oil oxidation of an oil-in-water emulsion containing iron was studied. The emulsion comprised tocopherol-stripped soybean oil (40 g), citrate buffer (60 g, pH 4.0), xanthan gum (35mg), and FeSO (0.5mg) with 80% ethanol extracts of rosemary (), basil (), peppermint (), thyme (), or oregano (). Hydroperoxide contents and -anisidine values were significantly (<0.05) lower in the emulsions with the added herb extracts compared with the control emulsions. The antioxidant activity of the basil and peppermint extracts containing higher proportions of rosmarinic acid was significantly higher (<0.05) than that of the other herb extracts, but the polyphenol degradation rate was not significantly different. The antioxidant activity of the basil and peppermint extracts showed concentration-dependence within 400 mg/kg. This study suggests that the oxidative stability of oil-inwater emulsion containing iron can be improved by addition of basil or peppermint extract.

Roles and action mechanisms of herbs added to the emulsion on its lipid oxidation

“…Lavender (Lavandula angustifolia) and thyme extracts showed higher antioxidant activity than rosemary extracts in the O/W emulsion (Gallego et al, 2013). The antioxidant activity of the peppermint or basil extract at 400 mg/kg was higher than that of rosemary, oregano, or thyme extract in the 40% soybean oil-in-water emulsions, and the antioxidant activity showed a concentration dependence within a range between 0 and 400 mg/kg (Kim and Choe, 2016). The antioxidant activity derived from herb extracts was different depending on the herb and the extracting solvents; non-polar extracts of barley with 80% acetone showed higher reducing power than those with 80% ethanol or methanol and water extracts, whereas the reverse phenomena were observed in hydroxyl or superoxide anion radical scavenging activity and metal chelating activity (Zhao et al, 2006).…”

Interaction effect of tocopherol homologs with peppermint extract on the iron-catalyzed oxidation of soybean oil-in-water emulsion

“…Soybean oil was a product of Samyang Corp. (Seoul, Korea) and tocopherols in the oil were completely removed using alumina column chromatography (Kim and Choe, 2016) by passing the oil through a glass column packed with silicic acid and aluminum oxide (Sigma-Aldrich Co., St. Louis, MO, USA). Dried peppermint (Mentha 9 piperita) was a product of the Florapharm (Schesslitz, Germany).…”

“…Emulsions were prepared with tocopherol-stripped soybean oil (400 g) and citrate buffer solution (pH 4.0, 600 g) according to the method of Kim and Choe (2016). Peppermint extract was obtained using 75% ethanol; dried peppermint, roughly ground in an Essence HR 2084 blender (Philips, Amsterdam, Netherlands), was mixed with 75% ethanol (1:10, w/v) at 25°C and 120 rpm for 12 h, and filtered, with a final solvent removal using a rotary evaporator (N-N series; Eyela, Tokyo, Japan) at 65°C.…”

“…Lipid oxidation of emulsions was evaluated based on the hydroperoxide contents and p-anisidine values as indicators for primary and secondary oxidation product generation, respectively. The hydroperoxide contents were determined by the ferric thiocyanate method (Kim and Choe, 2016) using a UV-visible spectrophotometer (UV-2700, Shimadzu Corp., Kyoto, Japan), and was expressed as cumene hydroperoxide (CuOOH; Sigma-Aldrich Co.). The p-anisidine value was determined spectrophotometrically according to the AOCS method Cd 18-90 (AOCS, 2006) after phase separation of emulsions (Min et al, 2003) and the instrument used was a UV-2700 spectrophotometer (Shimadzu Corp.) at 350 nm.…”

“…Ethanol extracts of peppermint and basil contained high amount of polyphenols ([ 40 g/kg) and improved the lipid oxidative stability of a soybean oil-in-water emulsion (Kim and Choe, 2016) through iron-chelating and radical scavenging . a-Tocopherol, rosmarinic acid, and caffeic acid at natural concentration present in the peppermint extract (400 mg/kg) acted as antioxidants in the iron-catalyzed oxidation of acidic soybean oil-in-water emulsion, with the highest contribution by a-tocopherol despite low concentration of \ 1 mg/kg (Lee and Choe, 2018).…”