The effect of microfiltration on color, flavor, and functionality of 80% whey protein concentrate

Abstract

The residual annatto colorant in fluid Cheddar cheese whey is bleached to provide a neutral-colored final product. Currently, hydrogen peroxide (HP) and benzoyl peroxide are used for bleaching liquid whey. However, previous studies have shown that chemical bleaching causes off-flavor formation, mainly due to lipid oxidation and protein degradation. The objective of this study was to evaluate the efficacy of microfiltration (MF) on norbixin removal and to compare flavor and functionality of 80% whey protein concentrate (WPC80) from MF whey to WPC80 from whey bleached with HP or lactoperoxidase (LP). Cheddar cheese whey was manufactured from colored, pasteurized milk. The fluid whey was pasteurized and fat separated. Liquid whey was subjected to 4 different treatments: control (no bleaching; 50°C, 1 h), HP (250 mg of HP/kg; 50°C, 1 h), and LP (20 mg of HP/kg; 50°C, 1 h), or MF (microfiltration; 50°C, 1 h). The treated whey was then ultrafiltered, diafiltered, and spray-dried to 80% concentrate. The entire experiment was replicated 3 times. Proximate analyses, color, functionality, descriptive sensory and instrumental volatile analysis were conducted on WPC80. The MF and HP- and LP-bleached WPC80 displayed a 39.5, 40.9, and 92.8% norbixin decrease, respectively. The HP and LP WPC80 had higher cardboard flavors and distinct cabbage flavor compared with the unbleached and MF WPC80. Volatile compound results were consistent with sensory results. The HP and LP WPC80 were higher in lipid oxidation compounds (especially heptanal, hexanal, pentanal, 1-hexen-3-one, 2-pentylfuran, and octanal) compared with unbleached and MF WPC80. All WPC80 had >85% solubility across the pH range of 3 to 7. The microstructure of MF gels determined by confocal laser scanning showed an increased protein particle size in the gel network. MF WPC80 also had larger storage modulus values, indicating higher gel firmness. Based on bleaching efficacy comparable to chemical bleaching with HP, flavor, and functionality results, MF is a viable alternative to chemical or enzymatic bleaching of fluid whey.

Sensory and Functionality Differences of Whey Protein Isolate Bleached by Hydrogen or Benzoyl Peroxide

“…A result of 12% norbixin destruction appears inconsistent with past studies, but previous studies have not addressed WPI. A large portion of the norbixin retained in the whey during the cheese make process is removed by microfiltration and discarded with the MF retentate (Qiu and others ). While the unbleached control was not chemically bleached, a study performed by Qiu and others () demonstrated that microfiltration reduced norbixin levels by approximately 40% in WPI.…”

“…A large portion of the norbixin retained in the whey during the cheese make process is removed by microfiltration and discarded with the MF retentate (Qiu and others ). While the unbleached control was not chemically bleached, a study performed by Qiu and others () demonstrated that microfiltration reduced norbixin levels by approximately 40% in WPI. The liquid whey was bleached before MF, which reduced norbixin concentration in both the serum and fat phase of the liquid whey.…”

Invited review: The effects of processing parameters on the flavor of whey protein ingredients

“…When used in the production of WPC 80 for norbixin removal, MF was as effective as HP but not as effective as the LP system. Both HP and LP bleached WPC 80 had higher cardboard and cabbage flavors compared with unbleached WPC 80 and a WPC 80 produced by microfiltration (Qiu et al, 2015).…”

Sensory Lexicons and Formation Pathways of Off-Aromas in Dairy Ingredients: A Review

“…Solvent-assisted flavor evaporation is also a good option because of its exhaustive volatile extraction and minimal thermal artifacts during isolation [98,99]. Many studies employed direct solvent extraction plus solvent-assisted flavor evaporation [20,21,23] or solid-phase microextraction [31,50,100,101] for determining off-aromas in dairy ingredients. The identification and quantitation of odorants, as previously discussed, is usually achieved through well-established flavor research instrumentation, such as gas chromatography-mass spectrometry (GC-MS), flame ionization detectors (GC-FIDs), or pulsed flame photometric detectors (GC-PFPDs) equipped with olfactometry.…”