title: Brown pigment formation in heated sugar-protein mixed suspensions containing unmodified and peptically modified whey protein concentrates.
abstract: Commercial whey protein concentrate (WPC) was modified by heating the acidified protein suspensions (pH 2.0) at 80 °C for 30 min and treating with pepsin at 37 °C for 60 min. Prior to spray-drying, such modification did not change the molecular weights (MWs) of whey proteins determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). After spray-drying the modified whey protein concentrate with trehalose excipient (MWPC-TH), it was found that the α-lactalbumin (α-La) was the major protein that was further hydrolyzed the most. The reconstituted MWPC-TH contained β-lactoglobulin (β-Lg) as the major protein and small molecular weight (MW) peptides of less than 6.5 kDa. The reconstituted MWPC-TH had higher NH2 group, Trolox equivalent antioxidant capacity (TEAC), lower exposed aromatic ring and thiol (SH) contents than did the commercial WPC. Kinetic studies revealed that the addition of MWPC-TH in fructose-glycine solution was able to reduce brown pigment formation in the mixtures heated at 80 to 95 °C by increasing the activation energy (Ea) of brown pigment formation due to the retardation of fluoresced advanced glycation end product (AGEs) formation. The addition of MWPC to reducing sugar-glycine/commercial WPC was also able to lower brown pigment formation in the sterilized (121 °C, 15 min) mixed suspensions containing 0.1 M reducing sugar and 0.5-1.0 % glycine and/or commercial (P < 0.05). It was demonstrated that the modification investigated in this study selectively hydrolyzed α-La and retained β-Lg for the production of antibrowning whey protein concentrate.
authors.affiliation: Department of Food Science and Technology, Faculty of Agro-Industry, Kasetsart University, 50 Phahonyothin Road, Chatuchak, Bangkok, 10900 Thailand.
authors.forename: Narumol
authors.initials: N
authors.lastname: Rongsirikul
authors.affiliation: Department of Food Science and Technology, Faculty of Agro-Industry, Kasetsart University, 50 Phahonyothin Road, Chatuchak, Bangkok, 10900 Thailand.
authors.forename: Parichat
authors.identifier: 0000-0002-7244-3594
authors.initials: P
authors.lastname: Hongsprabhas
keywords: AGEs; Browning; Hydrolysate; Maillard reaction; Whey protein