title: Enrichment and Purification of Casein Glycomacropeptide from Whey Protein Isolate Using Supercritical Carbon Dioxide Processing and Membrane Ultrafiltration.
abstract: Whey protein concentrates (WPC) and isolates (WPI), comprised mainly of β-lactoglobulin (β-LG), α-lactalbumin (α-LA) and casein glycomacropeptide (GMP), are added to foods to boost nutritional and functional properties. Supercritical carbon dioxide (SCO₂) has been shown to effectively fractionate WPC and WPI to obtain enriched fractions of α-LA and β-LG, thus creating new whey ingredients that exploit the properties of the individual component proteins. In this study, we used SCO₂ to further fractionate WPI via acid precipitation of α-LA, β-LG and the minor whey proteins to obtain GMP-enriched solutions. The process was optimized and α-LA precipitation maximized at low pH and a temperature (T) ≥65 °C, where β-LG with 84% purity and GMP with 58% purity were obtained, after ultrafiltration and diafiltration to separate β-LG from the GMP solution. At 70 °C, β-LG also precipitated with α-LA, leaving a GMP-rich solution with up to 94% purity after ultrafiltration. The different protein fractions produced with the SCO₂ process will permit the design of new foods and beverages to target specific nutritional needs.
authors.affiliation: Dairy and Functional Foods Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA. Laetitia.bonnaillie@ars.usda.gov.
authors.forename: Laetitia M
authors.initials: LM
authors.lastname: Bonnaillie
authors.affiliation: Dairy and Functional Foods Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA. phoebe.qi@ars.usda.gov.
authors.forename: Phoebe
authors.initials: P
authors.lastname: Qi
authors.affiliation: Dairy and Functional Foods Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA. edward.wickham@ars.usda.gov.
authors.forename: Edward
authors.initials: E
authors.lastname: Wickham
authors.affiliation: Dairy and Functional Foods Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA. Peggy.tomasula@ars.usda.gov.
authors.forename: Peggy M
authors.initials: PM
authors.lastname: Tomasula
keywords: casein glycomacropeptide; fractionation process; membrane filtration; supercritical carbon dioxide; whey proteins; β-lactoglobulin