Figure 1.

Whey protein processing. (a) Whey protein concentrate (WPC) was obtained from raw bovine milk by cold membrane filtration. The WPC was first mildly pasteurized for 30 s at 37 °C, after which a part of the WPC was extensively heat-treated for 6 min at 80 °C. (b) The level of carboxymethyllysine (CML, µg/mL) measured by ultra-fast liquid chromatography/fluorescence UFLC/Flu) in both mildly pasteurized (MP-WPC) and more extensively heated WPC (EH-WPC). (c) Soluble protein (% of total WPC protein) at pH 7.1 and pH 4.6, determined by the DUMAS method. (d) Representative sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) gel of EH-WPC and MP-WPC at pH 7.1 under reducing (+2ME) and non-reducing conditions, with (e) corresponding densitometric analysis. Black arrows indicate decrease in peak intensity for EH-WPC specifically. n = 3, ** p < 0.05, *** p < 0.01 based on t-test between EH-WPC and MP-WPC. BSA = bovine serum albumin, IgG (HC) = immunoglobulin G (heavy chain), βCAS = β-casein, βLG = β-lactoglobulin, αLA = α-lactalbumin. kDa = kilodaltons, 2ME = 2-mercaptoethanol.