ANTIOXIDANT ACTIVITY OF A MAILLARD-TYPE PHOSVITIN-GALACTOMANNAN CONJUGATE WITH EMULSIFYING PROPERTIES AND HEAT-STABILITY

Egg yolk phosvitin was conjugated with galactomannan through a control led Maillard reaction at 60 degrees C in 79% relative humidity for 1 w eek. Antioxidant activity of phosvitin and phosvitin-galactomannan con jugate (PGC) was assessed using a powdered model linoleic acid system. The conjugation reaction significantly (P < 0.05) enhanced the antiox idant activity of phosvitin. One-tenth percent PGC suppressed the rela tive lipid oxidation rate catalyzed with 1 mg/L Fe2+ to 75% and 73% in thiobarbituric acid and peroxide values, respectively, compared to th ose of a simple phosvitin-galactomannan mixture after 3 days at 20 deg rees C. The antioxidant effect of PGC was not affected by autoclaving (121 degrees C, 1.2 atm for 15 min), whereas the same treatment when a pplied to native phosvitin resulted in a lower affinity to inhibit iro n-catalyzed lipid oxidation. The conjugation of phosvitin with galacto mannan significantly (P < 0.05) improved both emulsifying activity and emulsion stability. The results demonstrate that the Maillard-type PG C can be used as an effective macromolecular antioxidant, with good em ulsifying properties and heat stability.