Enzymatic Modification of Lecithin for Improved Antioxidant Activity in Combination with Tocopherol in Emulsions and Bulk Oil

Abstract

Oxidized α-tocopherol can be regenerated by phosphatidylethanolamine (PE), but current commercial sources of PE are too expensive for use as a food additive. The present study aims to determine the optimal reaction conditions for generating high PE lecithin (MHPEL) enzymatically and to validate the MHPEL’s synergism with tocopherol in delaying lipid oxidation in an oil-in-water emulsion system at pH 7 and 4 and in bulk oil. Under optimal conditions of pH 9.0, 37 °C and 4 h, a MHPEL with ∼71.6% PE was obtained from 96% phosphatidylcholine lecithin using phospholipase D from Streptomyces chromofuscus. Mixed tocopherols (300 μmol/kg oil) and MHPEL (1500 μmol/kg oil) synergistically increased both the hydroperoxide and hexanal lag phase of lipid oxidation in stripped soybean oil-in-water emulsions at pH 7 by 3 days. At pH 4, this combination increased the hydroperoxide and hexanal lag phases by 3 and 2 days, respectively. The combination of 50 μmol/kg oil α-tocopherol and 1000 μmol/kg oil MHPEL also synergistically increased the hydroperoxide (5 days) and hexanal (4 days) lag phases in stripped bulk soybean oil. This approach represents a potential clean-label antioxidant system that could have commercial applications to decrease food waste.

Synergistic Mechanisms of Interactions between Myricetin or Taxifolin with α-Tocopherol in Oil-in-Water Emulsions

“…The investigation of antioxidant activity at pH 4.0 is critical because many food emulsions, including salad dressings and condiments have a pH range of 2.9–4.4 Figure showed that α-tocopherol (30 μM) treated emulsion samples had lag phases of 32 days for lipid hydroperoxides and 33 days for headspace hexanal production, compared to lag phases of 1 and 2 days for the control group.…”

Analysis of the mechanism of antioxidant synergism between α‐tocopherol and myricetin in bulk oil

“…We did not perform additional research for α-tocopherol and taxifolin combinations in this section of the experiment because synergism was not observed in stripped soybean oils, as shown in Figure 3. We particularly used phosphatidylcholine (PC) instead of phosphatidylserine (PS) or phosphatidylethanolamine (PE) because PE and PS contributes to the synergistic activity by regenerating tocopherols in bulk oils and emulsions, whereas PC shows no effect in oxidative stability in the presence of tocopherols (Cui et al, 2015;Culler et al, 2022;Doert et al, 2012;Takenaka et al, 2007). The formation of lipid hydroperoxides and headspace hexanal was analyzed in the presence of 1000 μM DC 4 PC with α-tocopherol and myricetin (Figure 5).…”