title: The dual effects of Maillard reaction and enzymatic hydrolysis on the antioxidant activity of milk proteins.
abstract: The objective of this study was to determine the enhanced effects on the biological characteristics and antioxidant activity of milk proteins by the combination of the Maillard reaction and enzymatic hydrolysis. Maillard reaction products were obtained from milk protein preparations, such as whey protein concentrates and sodium caseinate with lactose, by heating at 55°C for 7 d in sodium phosphate buffer (pH 7.4). The Maillard reaction products, along with untreated milk proteins as controls, were hydrolyzed for 0 to 3h with commercial proteases Alcalase, Neutrase, Protamex, and Flavorzyme (Novozymes, Bagsværd, Denmark). The antioxidant activity of hydrolyzed Maillard reaction products was determined by reaction with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, their 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, and the ability to reduce ferric ions. Further characteristics were evaluated by the o-phthaldialdehyde method and sodium dodecyl sulfate-PAGE. The degree of hydrolysis gradually increased in a time-dependent manner, with the Alcalase-treated Maillard reaction products being the most highly hydrolyzed. Radical scavenging activities and reducing ability of hydrolyzed Maillard reaction products increased with increasing hydrolysis time. The combined products of enzymatic hydrolysis and Maillard reaction showed significantly greater antioxidant activity than did hydrolysates or Maillard reaction products alone. The hydrolyzed Maillard reaction products generated by Alcalase showed significantly higher antioxidant activity when compared with the other protease products and the antioxidant activity was higher for the whey protein concentrate groups than for the sodium caseinate groups. These findings indicate that Maillard reaction products, coupled with enzymatic hydrolysis, could act as potential antioxidants in the pharmaceutical, food, and dairy industries.
authors.affiliation: Research and Development Center, Seoul Dairy Cooperative, Ansan, Kyunggi 425-839, South Korea. Division of Food Bioscience and Technology, College of Life Science and Biotechnology, Korea University, Seoul 136-701, South Korea
authors.forename: N S
authors.initials: NS
authors.lastname: Oh
authors.forename: H A
authors.initials: HA
authors.lastname: Lee
authors.forename: J Y
authors.initials: JY
authors.lastname: Lee
authors.forename: J Y
authors.initials: JY
authors.lastname: Joung
authors.forename: K B
authors.initials: KB
authors.lastname: Lee
authors.forename: Y
authors.initials: Y
authors.lastname: Kim
authors.forename: K W
authors.initials: KW
authors.lastname: Lee
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D006868:Hydrolysis / Q000187:drug effects; D007785:Lactose / Q000378:metabolism; D015416:Maillard Reaction / Q000187:drug effects; D008894:Milk Proteins / Q000378:metabolism / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D000067816:Whey Proteins
chemical_list: D000975:Antioxidants; D008894:Milk Proteins; D000067816:Whey Proteins; D007785:Lactose
keywords: Maillard reaction; antioxidant activity; enzymatic hydrolysis; milk protein