title: Interactions of vitamin D3 with bovine beta-lactoglobulin A and beta-casein.
abstract: It is of nutritional significance to fortify processed dairy products (e.g., cheese, yogurt, and ice cream) with vitamin D3; however, the inherent complexity of these foods may influence the stability and bioavailability of this nutrient. In the present study, the interactions of vitamin D3 with beta-lactoglobulin A and beta-casein were investigated under various environmental conditions (i.e., pH and ionic strength) using fluorescence and circular dichroism spectroscopic techniques. The results indicated that vitamin D3 was bound to both beta-lactoglobulin A and beta-casein depending on the solution conditions. The apparent dissociation constants ranged from 0.02 to 0.29 microM for beta-lactoglobulin A, whereas the beta-casein apparent dissociation constants ranged from 0.06 to 0.26 microM. The apparent mole ratios were also comparable, i.e., 0.51-2.04 and 1.16-2.05 mol of vitamin D3 were bound per mole of beta-lactoglobulin A and beta-casein, respectively. It was concluded that these interactions may strongly influence vitamin D3 stability and, hence, bioavailability in processed dairy products.
authors.affiliation: Department of Food Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Forrest
authors.forename: Rickey Y
authors.initials: RY
authors.lastname: Yada
authors.forename: Dérick
authors.initials: D
authors.lastname: Rousseau
mesh_terms: D000818:Animals; D002364:Caseins / Q000737:chemistry*; D002417:Cattle; D002762:Cholecalciferol / Q000737:chemistry*; D002942:Circular Dichroism; D003611:Dairy Products / Q000032:analysis; D004347:Drug Interactions; D005527:Food, Fortified; D006863:Hydrogen-Ion Concentration; D007782:Lactoglobulins / Q000737:chemistry*; D009994:Osmolar Concentration; D013050:Spectrometry, Fluorescence
chemical_list: D002364:Caseins; D007782:Lactoglobulins; D002762:Cholecalciferol