Effect of layer-by-layer coatings and localization of antioxidant on oxidative stability of a model encapsulated bioactive compound in oil-in-water emulsions.
Oxidation of encapsulated bioactives in emulsions is one of the key challenges that limit shelf-life of many emulsion containing products. This study seeks to quantify the role of layer-by-layer coatings and localization of antioxidant molecules at the emulsion interface in influencing oxidation of the encapsulated bioactives. Oxidative barrier properties of the emulsions were simulated by measuring the rate of reaction of peroxyl radicals generated in the aqueous phase with the encapsulated radical sensitive dye in the lipid core of the emulsions. The results of peroxyl radical permeation were compared to the stability of encapsulated retinol (model bioactive) in emulsions. To evaluate the role of layer-by-layer coatings in influencing oxidative barrier properties, radical permeation rates and retinol stability were evaluated in emulsion formulations of SDS emulsion and SDS emulsion with one or two layers of polymers (ϵ-polylysine and dextran sulfate) coated at the interface. To localize antioxidant molecules to the interface, gallic acid (GA) was chemically conjugated with ϵ-polylysine and subsequently deposited on SDS emulsion based on electrostatic interactions. Emulsion formulations with localized GA molecules at the interface were compared with SDS emulsion with GA molecules in the bulk aqueous phase. The results of this study demonstrate the advantage of localization of antioxidant at the interface and the limited impact of short chain polymer coatings at the interface of emulsions in reducing permeation of radicals and oxidation of a model encapsulated bioactive in oil-in-water emulsions.
Department of Food Science and Technology, University of California-Davis, Davis CA 95616, United States.
Yuanjie
Y
Pan
Department of Food Science and Technology, University of California-Davis, Davis CA 95616, United States; Department of Biological and Agricultural Engineering, University of California-Davis, Davis CA 95616, United States. Electronic address: nnitin@ucdavis.edu.
N
N
Nitin
D000975:Antioxidants / Q000008:administration & dosage / Q000737:chemistry*; D004396:Coloring Agents; D004339:Drug Compounding; D004655:Emulsions; D005707:Gallic Acid / Q000737:chemistry; D009821:Oils; D010084:Oxidation-Reduction; D010545:Peroxides; D011107:Polylysine / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013501:Surface-Active Agents; D014801:Vitamin A / Q000008:administration & dosage / Q000737:chemistry; D014867:Water
D000975:Antioxidants; D004396:Coloring Agents; D004655:Emulsions; D009821:Oils; D010545:Peroxides; D017382:Reactive Oxygen Species; D013501:Surface-Active Agents; D014867:Water; D014801:Vitamin A; D011107:Polylysine; C049375:perhydroxyl radical; D012967:Sodium Dodecyl Sulfate; D005707:Gallic Acid
Bioactive compounds; Emulsions with structured interfacial coatings; Free radical induced oxidation; Layer-by-layer coatings; Localization of antioxidant