Manufacture of Undenatured Whey Protein Concentrates by Ultrafiltration and Spray Drying: 1. Low-Protein Powders

Concentrated whey solution containing 7.9% protein (21.6% total solids) was recovered from Cheddar cheese whey, using tubular cellulose acetate ultrafiltration membranes with a nominal NaC1 rejection rating of 10%. This concentrated whey was spray-dried directly, without prior evaporation, at air inlet temperatures of 150°, 170° and 200°C. The three Moorepark whey protein concentrates (MWPC) contained 28 to 30% protein, 53 to 54% lactose, 3.8 to 4.0% minerals and 4 to 5% fat. The moisture levels of the powders ranged from 1.50 to 4.60% and were inversely related to drying temperatures. The degree of whey protein denaturation increased directly with drying temperatures and varied from 8.18 to 16.31% for pH 4.6 filtrates, and from 6.15 to 11.72% for saturated NaC1 filtrates. The saturated NaC1 filtrates gave higher soluble-protein levels than their pH 4.6 counterparts, which resulted in reduced denaturation levels of 18 to 28%. The 'low-heat' category of the MWPCs was supported by excellent water-solubility characteristics under neutral and acid pH values. Mineral levels, functionality and nutritional profiles of the MWPCs indicate their potential value in human nutrition.