title: Characterization of catechin-α-lactalbumin conjugates and the improvement in β-carotene retention in an oil-in-water nanoemulsion.
abstract: The goal of this study was to prepare and characterize α-lactalbumin (ALA)-catechin conjugates as a novel emulsifier in improving the retention of β-carotene (BC) in nanoemulsions via a free radical method. Covalent modification was observed and at least one catechin molecule was binding with ALA according to ESI-MS results. Far-UV CD indicated that the secondary structure of ALA was changed after conjugation. The Z-average particle diameters of nanoemulsions stabilized with ALA and ALA-catechin conjugates were 158.8 and 162.7 nm, respectively. The increase of mean particle size and the degradation of BC at 50°C were both larger than at 25°C during 30 days storage. BC retention stabilized with ALA-catechin conjugates was appreciably greater than ALA (control), which was attributed to the increase of ALA's radicals-scavenging and free metal ion binding ability after grafting with catechin. The chemical antioxidant activities of ALA-catechin conjugates were increased with increasing concentrations from 0.1 to 1.0mg/ml. In general, labile phytochemicals, like BC, can be protected against oxidation during storage by proteins-polyphenols conjugates without any side effects.
authors.affiliation: College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China. Electronic address: yijiangjnu@gmail.com.
authors.forename: Jiang
authors.initials: J
authors.lastname: Yi
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
authors.forename: Yuting
authors.initials: Y
authors.lastname: Fan
authors.affiliation: Western Regional Research Center, ARS, USDA, Albany, CA 94710, United States.
authors.forename: Yuzhu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China. Electronic address: snowyzlj@163.com.
authors.forename: Liqing
authors.initials: L
authors.lastname: Zhao
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D002392:Catechin / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D004655:Emulsions; D005609:Free Radicals; D007768:Lactalbumin / Q000737:chemistry*; D058726:Nanoconjugates / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D021241:Spectrometry, Mass, Electrospray Ionization; D019207:beta Carotene / Q000032:analysis* / Q000737:chemistry
chemical_list: D000975:Antioxidants; D004655:Emulsions; D005609:Free Radicals; D058726:Nanoconjugates; D019207:beta Carotene; D002392:Catechin; D007768:Lactalbumin
keywords: Chemical stability; Nano-encapsulation; SDS–PAGE; α-Lactalbumin; β-Carotene