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.
Highlights
With the introduction of processing methods, such as microfiltration and ultrafiltration, whey protein concentrates (WPC) with protein contents ranging from 35% to 85% and whey protein isolates (WPI) with protein contents greater than 90% are available to improve the functional and nutritional properties of foods
To circumvent the problems associated with variations in the whey products, several processes have been developed [1] to fractionate the proteins found in WPC and WPI and emphasize the production of an α-LA-enriched fraction and a β-LG-enriched fraction [3,4,5]
The α-LA-enriched fraction has been proposed for use in humanized infant formulations and for foods for children and seniors [6,7,8,9], and α-LA is high in branched chain amino acids
Summary
With the introduction of processing methods, such as microfiltration and ultrafiltration, whey protein concentrates (WPC) with protein contents ranging from 35% to 85% and whey protein isolates (WPI) with protein contents greater than 90% are available to improve the functional and nutritional properties of foods. The α-LA-enriched fraction has been proposed for use in humanized infant formulations and for foods for children and seniors [6,7,8,9], and α-LA is high in branched chain amino acids. The β-LG enriched fraction may be used to enhance gel strength in foods, but more importantly, it is high in branched chain amino acids, leucine and other essential amino acids [10,11], which may be used to fortify foods or in the creation of foods that target specific nutritional needs
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