Antioxidant Activity of a Maillard-Type Phosvitin−Galactomannan Conjugate with Emulsifying Properties and Heat Stability

Egg yolk phosvitin was conjugated with galactomannan through a controlled Maillard reaction at 60 °C in 79% relative humidity for 1 week. Antioxidant activity of phosvitin and phosvitin−galactomannan conjugate (PGC) was assessed using a powdered model linoleic acid system. The conjugation reaction significantly ( P <0.05) enhanced the antioxidant activity of phosvitin. One-tenth percent PGC suppressed the relative lipid oxidation rate catalyzed with 1 mg/L Fe 2+ to 75% and 73% in thiobarbituric acid and peroxide values, respectively, compared to those of a simple phosvitin−galactomannan mixture after 3 days at 20° C. The antioxidant effect of PGC was not affected by autoclaving (121 °C, 1.2 atm for 15 min), whereas the same treatment when applied to native phosvitin resulted in a lower affinity to inhibit iron-catalyzed lipid oxidation. The conjugation of phosvitin with galactomannan significantly ( P < 0.05) improved both emulsifying activity and emulsion stability. The results demonstrate that the Maillard-type PGC can be used as an effective macromolecular antioxidant, with good emulsifying properties and heat stability.