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.

Pilot Study on the Removal of Lactic Acid and Minerals from Acid Whey Using Membrane Technology

“…Maillard reactions may take place between these fixed charges and the lactose present in acid whey, producing N-containing polymers known as melanoidins, which are brown in color. 26 While Maillard reactions are usually favored only above 140 °C, Choi and Moon 27 suggest that the temperature of the IEMs may be higher than the bulk solutions when subjected to electrical fields and this may have accelerated their formation. Maillard reactions can be observed by the formation of new peaks in the FTIR spectrum between 1630 and 1650 cm −1 (C=N stretching) 28 as is indeed observed for the used membranes in Figure 7b.…”

“…AHA membranes are known to incorporate charged amine and/or amide groups, such as −NH 3 + , – NRH 2 + , −NR 2 H + , and −NH 3 + . Maillard reactions may take place between these fixed charges and the lactose present in acid whey, producing N-containing polymers known as melanoidins, which are brown in color . While Maillard reactions are usually favored only above 140 °C, Choi and Moon suggest that the temperature of the IEMs may be higher than the bulk solutions when subjected to electrical fields and this may have accelerated their formation.…”

Antioxidant and Functional Activities of MRPs Derived from Different Sugar–Amino Acid Combinations and Reaction Conditions

“…The activation energies for the Maillard reaction activation energy cover a wide range of 23–238 kJ/mol [ 41 ], and are dependent on reaction conditions. For example, an activation energy of 170 kJ/mol reported using a sugar–whey protein mixture varies greatly from what is required to bake cookies (e.g., 10.6 kJ/mol) [ 42 ]. In the present study, the addition of Alphacel with different reactants appeared to reduce to the rate of the Maillard browning during heating according to observed recovery of soluble browning products, along with relative sugar losses and color changes.…”

Conventional and alternative concentration processes in milk manufacturing: a comparative study on dairy properties

“…The lactose fraction has also proven to be responsible for important roles in the sensory, nutritional, functional, and physicochemical properties of powdered dairy products (Fialho et al, 2018;Park et al, 2016;Rongsirikul & Hongsprabhas, 2016;Zhou & Langrish, 2021). Depending on the processing conditions, in addition to high temperatures, water evaporation, high concentration of lactose and lysine-rich proteins, Maillard reactions may occur and causes several effects, including the unattractive formation of melanoidins (nitrogen-containing brow pigments), the loss of nutritional value, changes in the sensory properties, presence of off-flavors and formation of potential mutagenic products (Perusko et al, 2021;Zhou & Langrish, 2021).…”