Dairy Foods: Filtration and Drying

Our objective was to determine if annatto color or bleaching had any influence on ultrafiltration (UF) flux during production of 80% whey protein concentrate (WPC) or 80% serum protein concentrate (SPC). Cheddar cheese whey (18 vats using 900 kg of whole milk each) and microfiltration (MF) permeate of skim milk (18 processing runs using 1000 kg of skim milk each) were produced. The 18 runs were divided into 3 replicates with 6 different treatments within each replicate. The 6 treatments within either the whey or MF permeate replicates were: 1) no annatto (NA), 2) NA + benzoyl peroxide (BPO), 3) NA + H2O2, 4) annatto (A), 5) A + BPO, and 6) A + H2O2. Approximately 700 kg of separated, treated whey or treated MF permeate was heated to 50°C and processed with the UF system in batch recirculation mode using a polyethersulfone spiral wound UF membrane (Model 3838, GEA NIRO Inc., Hudson, WI) with a nominal pore size of 10,000 Da. Addition of annatto color had little or no effect (P > 0.05) on UF flux. Bleaching separated Cheddar cheese whey or MF permeate with or without added color improved (P < 0.05) UF flux during processing to produce 80% protein concentrates. Generally, H2O2 produced higher fluxes than BPO treatments (P < 0.05) and BPO increased SPC production fluxes to a lesser extent (P < 0.05) than it did WPC production fluxes. Relative to the flux of unbleached whey (about 15 L/ m2h), the bleached whey had a flux of about 20 to 23 L/m2h. Water flux before processing, after processing, and after final cleaning were measured at 50°C. The water flux after cleaning restored flux to the level before processing whey or permeate. The flux after processing (i.e., fouled water flux) demonstrated differences in fouling and loss of water permeability that were consistent with differences resulting from the bleaching treatments. Little, if any, effect of the annatto on fouled water flux was observed.