Effects of Wheat Bran-Derived Alkylresorcinols on the Physical and Oxidative Stability of Oil-in-Water Emulsions as related to pH

Alkylresorcinols (ARs), a homolog series of phenolipids naturally occurring in many by-products, can meet the high demand of the food industry for natural antioxidants. In this study, ARs (C17-C25) were isolated from wheat bran, and their antioxidant activity was tested in oil-in-water emulsions at pH 3.5 and pH 7.0 at two concentrations (15 and 30 mg/L of emulsion) during 14 days of storage at 35 °C. Results revealed that lipid oxidation was affected by both ARs concentration and pH of the emulsion. Indeed, when ARs were added, a significant suppression of hydroperoxides and aldehydes (hexanal and nonanal) formation with a consequent prolongation of their lag phases (5-fold) was observed at pH 3.5, while at pH 7.0 the lag phases were doubled. No influence of ARs on emulsion particle size was found. The present work demonstrated how ARs could represent sustainable and innovative natural antioxidants for emulsion-based food.