The Effect of Norbixin Destruction or Removal on Flavor and Functionality of 80% Whey Protein Concentrate
The residual annatto colorant (norbixin) in fluid Cheddar cheese whey is bleached to provide a neutral-colored final product. Currently, chemical and enzymatic applications are utilized for bleaching liquid whey. These approaches bleach by free radical formation and can cause off-flavors due to lipid oxidation and protein degradation. The objective of this study was to compare three bleaching/norbixin removal methods: hydrogen peroxide (HP), lactoperoxidase (LP), and microfiltration (MF), and their effects on the flavor and functionality of 80% whey protein concentrate (WPC80). Cheddar cheese whey was manufactured from colored, pasteurized milk. The fluid whey was pasteurized and fat separated. Whey was subjected to 1 of 4 different treatments: Control (no bleaching; 50°C, 1h), HP (250 mg hydrogen peroxide/kg; 50°C, 1h), LP (20 mg hydrogen peroxide/kg; 50°C, 1h), or MF (microfiltration; 50°C, 1h). The treated whey was then ultrafiltered, diafiltered, and spray-dried to 80% whey protein concentrate (WPC80). The entire experiment was replicated 3 times. Proximate analysis, color, functionality, descriptive sensory and instrumental volatile analysis were conducted on WPC80. Norbixin was decreased by 50, 46 and 95% for MF, HP, and LP bleached WPC80 treatments, respectively (p<0.05). The HP and LP WPC80 had higher cardboard flavor 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, octanal) compared to unbleached and MF WPC80. Protein solubility of WPC80 at various pH values was not different (p>0.05). All WPC80 had > 85% solubility at the pH range evaluated. Gelation under all conditions showed similar trends in small strain viscoelastic properties (p>0.05). Based on bleaching efficacy, flavor and functionality results, MF may be a viable alternative to chemical or enzymatic bleaching of fluid whey.
Keywords: whey bleaching, functionality, flavor