title: Comparison of Antioxidant Activities of Hydrolysates of Domestic and Imported Skim Milk Powders Treated with Papain.
abstract: Milk proteins have many potential sequences within their primary structure, each with a specific biological activity. In this study, we compared and investigated the bioactivities of hydrolysates of the domestic (A, B) and imported (C, D) skim milk powders generated using papain digestion. MALDI-TOF analysis revealed that all milk powder proteins were intact, indicating no autolysis. Electrophoretic analysis of hydrolysates showed papain treatment caused degradation of milk proteins into peptides of various size. The antioxidant activity of the hydrolysates, determined using 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and total phenolic contents (TPC) assays, increased with incubation times. In all skim milk powders, the antioxidant activities of hydrolysates were highest following 24 h papain treatment (TPC: A, 196.48 μM GE/L; B, 194.52 μM GE/L; C, 194.76 μM GE/L; D, 163.75 μM GE/L; ABTS: A, 75%; B, 72%; C, 72%; D, 57%). The number of peptide derived from skim milk powders, as determined by LC-MS/MS, was 308 for A, 283 for B, 208 for C, and 135 for D. Hydrolysate A had the highest antioxidant activity and the most potential antioxidant peptides amongst the four skim milk powder hydrolysates. A total of 4 β-lactoglobulin, 4 αs1-casein, and 56 β-casein peptide fragments were identified as potential antioxidant peptides in hydrolysate A by LC-MS/MS. These results suggest that domestic skim milk could have applications in various industries, i.e., in the development of functional foods.
authors.affiliation: Animal Products and Development Division, National Institute of Animal Science, RDA, Suwon 441-706, Korea; Department of Food Bioscience and Technology, Korea University, Seoul 136-701, Korea.
authors.forename: Go Eun
authors.initials: GE
authors.lastname: Ha
authors.affiliation: Animal Products and Development Division, National Institute of Animal Science, RDA, Suwon 441-706, Korea; Imported Food Analysis Division, Gwangju Regional Food and Drug Administration, Gwangju 500-480, Korea.
authors.forename: Oun Ki
authors.initials: OK
authors.lastname: Chang
authors.affiliation: Animal Products and Development Division, National Institute of Animal Science, RDA, Suwon 441-706, Korea.
authors.forename: Gi Sung
authors.initials: GS
authors.lastname: Han
authors.affiliation: Animal Products and Development Division, National Institute of Animal Science, RDA, Suwon 441-706, Korea.
authors.forename: Jun Sang
authors.initials: JS
authors.lastname: Ham
authors.affiliation: Animal Products and Development Division, National Institute of Animal Science, RDA, Suwon 441-706, Korea.
authors.forename: Beom-Young
authors.initials: BY
authors.lastname: Park
authors.affiliation: Animal Products and Development Division, National Institute of Animal Science, RDA, Suwon 441-706, Korea.
authors.forename: Seok-Geun
authors.initials: SG
authors.lastname: Jeong
keywords: antioxidant activity; antioxidant peptides; hydrolysis; papain; skim milk powder