title: Characterization of milk proteins-lutein complexes and the impact on lutein chemical stability.
abstract: In this study, the interaction of WPI (whey protein isolate) and SC (sodium caseinate) with hydrophobic lutein was investigated through UV-vis spectroscopy and circular dichroism (CD) as well as fluorescence. The effects on lutein's chemical stability were also examined. The decrease of turbidity of lutein suggested that lutein's aqueous solubility was improved after binding with milk proteins. CD analysis indicated lutein had little impact on the secondary structures of both proteins. Different preparation methods have significant impacts on the binding constant. Fluorescence results indicated that WPI and SC interact with lutein by hydrophobic contacts. Milk proteins have protective effects on lutein against oxidation and decomposition, and SC showed better capability in protecting lutein from oxidation than WPI during 16 days storage. The lutein's chemical stability was increased with increasing of proteins concentration. The results indicated that milk proteins may act as effective carriers for lipophilic nutraceuticals.
authors.affiliation: College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
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: Wallace
authors.initials: W
authors.lastname: Yokoyama
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: D002364:Caseins / Q000737:chemistry*; D014975:Lutein / Q000737:chemistry*; D008894:Milk Proteins / Q000737:chemistry*; D000067816:Whey Proteins / Q000737:chemistry*
chemical_list: D002364:Caseins; D008894:Milk Proteins; D000067816:Whey Proteins; D014975:Lutein
keywords: Chemical stability; Lutein; Secondary structure; Sodium caseinate; Whey protein isolate