Fig. 3.

Effect of pH on the polyphenol content of soybean oil-in-water emulsion (4:6, w/w) with added peppermint extract (400 mg/kg) during oxidation at 25 °C in the dark (A) without or (B) with added iron at 5 mg/kg (filled square; pH 2.6, filled circle; pH 4.0, triangle; pH 6.0). Different letters on the line are significantly different values among samples by Duncan’s multiple range test at 5%