title: Antioxidant activities of buttermilk proteins, whey proteins, and their enzymatic hydrolysates.
abstract: The oxygen radical absorbance capacities (ORAC) and metal chelating capacities (MCC) of protein concentrates prepared from buttermilk and cheese whey by ultrafiltration were compared with those of skim milk protein. Samples were also heat-denatured and hydrolyzed by pepsin for 2 h followed by trypsin for 3 h. The highest MCC was obtained for hydrolyzed skim milk protein. ORAC values ranged from 554.4 to 1319.6 μmol Trolox equivalents/g protein, with the highest value obtained for hydrolyzed buttermilk protein. Liquid-phase isoelectric focusing (IEF) of this hydrolysate yielded peptide fractions with lower ORAC values. LC-MS analysis of the hydrolyzed skim milk and buttermilk proteins and IEF fractions of the latter showed that peptides derived from milk fat globule membrane proteins, primarily butyrophilin, could be responsible for the superior antioxidant activity of buttermilk. These results suggest overall that hydrolyzed buttermilk protein could be used as a source of natural antioxidants.
authors.affiliation: STELA Dairy Research Center and Institute of Nutraceuticals and Functional Foods (INAF), Université Laval, Quebec City, QC, Canada G1V 0A6.
authors.forename: Valérie
authors.initials: V
authors.lastname: Conway
authors.forename: Sylvie F
authors.initials: SF
authors.lastname: Gauthier
authors.forename: Yves
authors.initials: Y
authors.lastname: Pouliot
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D002611:Cheese / Q000032:analysis; D043302:Cultured Milk Products / Q000737:chemistry*; D005520:Food Preservatives / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D057141:Food, Preserved / Q000032:analysis; D007502:Iron Chelating Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D008894:Milk Proteins / Q000737:chemistry* / Q000378:metabolism; D010434:Pepsin A / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D011489:Protein Denaturation; D011492:Protein Hydrolysates / Q000737:chemistry* / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D000067816:Whey Proteins
chemical_list: D000975:Antioxidants; D005520:Food Preservatives; D007502:Iron Chelating Agents; D008894:Milk Proteins; D010446:Peptide Fragments; D011492:Protein Hydrolysates; D000067816:Whey Proteins; D014357:Trypsin; D010434:Pepsin A