Phenolic-rich mustard extract significantly improved lipid oxidation in acidic pea protein-stabilized flaxseed-oil-in-water beverage emulsion

Abstract: Flaxseed oil (FO), as a plant-based source of ω-3 alpha-linolenic acid, can be used as a functional ingredient in the formulation of healthy foods. However, FO is susceptible to oxidation, forming unfavorable off-flavors. Moreover, even higher susceptibility of FO when dispersed in an aqueous medium limits its application in beverages. Therefore, there is an intense need to provide oxidative stability to FO when incorporated in aqueous-based food systems. In this project, our aim was to develop a physiochemically stable flaxseed oil-in-water (FO/W) emulsion for delivering ω-3 fatty acid to beverages. For that to happen, it was crucial to select appropriate antioxidants to mix with FO before emulsification. A phenolic-rich mustard extract (PME) as a natural antioxidant with total phenolic content, DPPH (2,2-diphenyl-1-picrylhydrazyl), DPPH radical scavenging activity and Ferric ion reducing power of 160.96±3.65 mgGAE/g, 18.4±0.4 μM TE/g, 70.85±0.9%, and 1076.68±1 μM TE/g, respectively, was added to FO before emulsification. Five wt% FO/W emulsion was stabilized using mildly fractionated soluble pea proteins at acidic pH, which was suitable for beverage applications. Along with physical stability assessments, the formation of primary and secondary oxidation products was monitored by peroxide value (PV) and p-Anisidine value (p-AV) measurements, respectively, at 4, 25 and 60°C during 28 days of storage. FO/W emulsion showed very good stability with a slight increase in surface average droplet size (D[3,2]) of 0.396 ±0.074 mm to 0.456± 0.09 mm during 28 days and against heat and low-salt concentrations. The FO/W emulsion was oxidatively stable, which showed the ability of PME to depress the oxidation equivalent to a synthetic antioxidant, TBHQ, at both lower and higher incubation temperatures. These findings can help the industry to provide a promising way to manufacture a physiochemically stable, healthy and functional beverage emulsion containing ω-3 fatty acid-rich oils and a mustard-derived natural antioxidant.