Erythorbyl laurate as a multifunctional food additive: interfacial characteristics and antioxidative activities in O/W emulsion

Abstract

Interfacial properties and antioxidant activities of erythorbyl laurate in O/W emulsion were identified. Surface tension, contact angle, and foaming ability were measured to investigate interfacial properties. Surface tension was decreased with increasing concentrations up to critical micelle concentration (CMC, 0.12 mM) and surface tension at CMC was 34 mN/m. Contact angle showed similar pattern with surface tension. Foaming ability of erythoryl laurate, Tween 20, and Triton X-100 solution was compared. Although no significant difference was observed in foaming capacity, foam produced by erythorbyl laurate had the highest half-life time among them. Based on the hydrophilic-lipophilic balance of erythorbyl laurate (9.8), soybean O/W emulsion (5:95, w/w) including 0.2%(w/w) of erythorbyl laurate was prepared. And the mean diameter (d 3,2) of erythorbyl laurate emulsion was 0.75 μm and spherical shape was observed by transmission electron microscopy. DPPH and ABTS assay were measured to observe its antioxidative activity and the EC50 of erythorbyl laurate was 331.43, and 425.95 μM, respectively. These results indicated that free-radical scavenging activity of erythorbyl laurate was retained after esterification. Antioxidative activity of erythorbyl laurate in O/W emulsion was also investigated after thermal oxidation (60oC) and 100 μM of riboflavin sensitized photooxidation. Antioxidant activity of erythorbyl laruate was compared with various emulsions stabilized with SDS, Tween 20, non-treated emulsifier for thermal oxidation. Erythorbyl laurate emulsion effectively inhibited lipid oxidation than those of other emulsions during storage under 11 days. Also, erythorbyl laurate emulsion had the most effective antioxidative activity among other emulsions in photooxidation during storage under 3,340 lux fluorescent light for 12 h. Moreover, emulsion stabilized by erythorbyl laurate presence at oil-water interface had higher antioxidative activity than Tween 20 emulsion with erythorbic acid. These results indicated that erythorbyl laurate can be used as a promising multi-functional emulsifier having an antioxidative activity.