title: Binding of 2-nonanone and milk proteins in aqueous model systems.
abstract: Interactions of the model flavor compound 2-nonanone with individual milk proteins, whey protein isolate (WPI), and sodium caseinate in aqueous solutions were investigated. A method to quantify the free 2-nonanone was developed using headspace solid-phase microextraction followed by gas chromatography with flame ionization detection. Binding constants (K) and numbers of binding sites (n) for 2-nonanone on the individual proteins were calculated. The 2-nonanone binding capacities decreased in the order bovine serum albumin > beta-lactoglobulin > alpha-lactalbumin > alpha s1-casein > beta-casein, and the binding to WPI was stronger than the binding to sodium caseinate. All proteins appeared to have one binding site for 2-nonanone per molecule of protein at the flavor concentrations investigated, except for bovine serum albumin, which possessed two classes of binding sites. The binding mechanism is believed to involve predominantly hydrophobic interactions.
authors.affiliation: Riddet Centre and Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11222, Palmerston North, New Zealand.
authors.forename: Janina
authors.initials: J
authors.lastname: Kühn
authors.forename: Xiang-Qian
authors.initials: XQ
authors.lastname: Zhu
authors.forename: Thérèse
authors.initials: T
authors.lastname: Considine
authors.forename: Harjinder
authors.initials: H
authors.lastname: Singh
mesh_terms: D002364:Caseins / Q000378:metabolism; D007659:Ketones / Q000378:metabolism*; D008894:Milk Proteins / Q000378:metabolism*; D011485:Protein Binding; D012996:Solutions; D014867:Water; D000067816:Whey Proteins
chemical_list: D002364:Caseins; D007659:Ketones; D008894:Milk Proteins; D012996:Solutions; D000067816:Whey Proteins; D014867:Water; C026636:2-nonanone