Copper-catalyzed oxidation of a structured lipid-based emulsion containing alpha-tocopherol and citric acid: influence of pH and NaCl.
The effects of salt and pH on copper-catalyzed lipid oxidation in structured lipid-based emulsions were evaluated. Ten percent oil-in-water emulsions were formulated with a canola oil/caprylic acid structured lipid and stabilized with 0.5% whey protein isolate. alpha-Tocopherol and citric acid were added to the emulsions to determine how changes in pH or the addition of NaCl affected their antioxidant activity. The peroxide values and anisidine values of emulsions stored at 50 degrees C were measured over an 8-day period. Increased lipid oxidation occurred in the pH 7.0 emulsions and when 0.5 M NaCl was added to the pH 3.0 samples. Adding alpha-tocopherol, citric acid, or a combination of the two compounds slowed the formation of hydroperoxides and their subsequent decomposition products in pH 3.0 emulsions.
Department of Food Science and Technology, The University of Georgia, Food Science Building, Athens, Georgia 30602-7610, USA.
Hannah T
HT
Osborn-Barnes
Casimir C
CC
Akoh
D000975:Antioxidants / Q000032:analysis; D002210:Caprylates / Q000737:chemistry; D019343:Citric Acid / Q000032:analysis* / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry*; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015227:Lipid Peroxidation; D008055:Lipids / Q000737:chemistry*; D008894:Milk Proteins / Q000737:chemistry; D010084:Oxidation-Reduction; D010545:Peroxides / Q000032:analysis; D000074262:Rapeseed Oil; D012965:Sodium Chloride / Q000494:pharmacology*; D000067816:Whey Proteins; D024502:alpha-Tocopherol / Q000032:analysis* / Q000737:chemistry
D000975:Antioxidants; D002210:Caprylates; D004655:Emulsions; D005229:Fatty Acids, Monounsaturated; D008055:Lipids; D008894:Milk Proteins; D010545:Peroxides; D000074262:Rapeseed Oil; D000067816:Whey Proteins; D019343:Citric Acid; D012965:Sodium Chloride; D003300:Copper; D024502:alpha-Tocopherol; C031492:octanoic acid