title: Interactions of milk α- and β-casein with malvidin-3-O-glucoside and their effects on the stability of grape skin anthocyanin extracts.
abstract: The interactions of α- and β-casein with malvidin-3-O-glucoside (MG), the major anthocyanin in grape skin anthocyanin extracts (GSAE), were examined at pH 6.3 by fluorescence, fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy. The binding constant (KS), binding force and effects of the interactions on the caseins conformation and GSAE stability were investigated. The results showed that α- and β-casein bound with MG via hydrophilic (van der Waals forces or hydrogen bonding) and hydrophobic interactions, respectively. α-Casein had a slightly stronger binding affinity toward MG than β-casein, with respective KS values of 0.51×10(3)M(-1) and 0.46×10(3)M(-1) at 297K. The secondary structures of α- and β-casein were changed by MG binding, with a decrease in α-helix and an increase in turn for α-casein and no change in α-helix and a decrease in turn for β-casein. The casein-anthocyanin interaction appeared to have a positive effect on the thermal, oxidation and photo stability of GSAE.
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, PR China. Electronic address: zyhe@jiangnan.edu.cn.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: He
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors.forename: Mingzhu
authors.initials: M
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors.forename: Maomao
authors.initials: M
authors.lastname: Zeng
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors.forename: Fang
authors.initials: F
authors.lastname: Qin
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, PR China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, PR China. Electronic address: chenjie@jiangnan.edu.cn.
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
mesh_terms: D000818:Animals; D000872:Anthocyanins / Q000737:chemistry*; D002364:Caseins / Q000737:chemistry*; D002942:Circular Dichroism; D005960:Glucosides / Q000737:chemistry*; D008892:Milk / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D027843:Vitis / Q000737:chemistry*
chemical_list: D000872:Anthocyanins; D002364:Caseins; D005960:Glucosides; C458419:malvidin-3-glucoside
keywords: Anthocyanin; Casein; Circular dichroism; Fluorescence spectroscopy; Fourier transform infrared; Interaction; Stability