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Microfiltered vs. Ion-Exchange Whey Protein Isolate
Several different technologies have been used to concentrate the protein in whey and remove fat, but the two that are currently used commercially are ion-exchange and microfiltration. The resulting whey protein isolates (WPI’s) are at least 90 percent protein, are essentially fat-free, and contain little or no lactose as well. Their whipping, gelling and similar functional properties are very much like egg white.
There are two basic methods for manufacturing whey protein isolate, ion-exchange and microfiltration.
In the most commonly used ion-exchange process, the whey is acidified to the point that most of the proteins have a net positive charge. The whey is then mixed with a resin, similar to that used for water softening, which has a negative charge. The positively charged proteins bind to the resin, allowing everything else to pass through. After the unbound materials (mostly fat and lactose) are washed out of the resin bed, the pH is increased to release the bound proteins, which are then concentrated by ultrafiltration and spray dried.
WPI prepared by ion-exchange normally contains the full complement of -lactoglobulin, the principal whey protein; but much of the -lactalbumin and some of the immunoglobulins and other protein components are lost. The changes in the amounts of individual whey proteins in ion-exchange WPI may have an effect on desired nutritional or “nutraceutical” value which must be determined on a case-by-case basis.
In the microfiltration process, fat is removed from whey by the use of special membranes that allow the proteins and other soluble components to pass through while retaining the fat globules. The lactose and soluble minerals are then removed by ultrafiltration and diafiltration. Unlike ion-exchange, the microfiltration process allows the whey proteins to be recovered in their natural proportions in the final product.
At equivalent protein contents, microfiltered WPI tends to be lower in fat content, while ion-exchange WPI tends to be lower in lactose. It may be of particular interest that glycomacropeptide (GMP), a product of the cheesemaking process, is not usually retained in whey protein isolates prepared by ion-exchange, but GMP comprises approximately 25% of the whey proteins retained during microfiltration. GMP is nutritious for the body, as it helps control gastrointestinal diseases.
Typical Concentrations of Whey Protein Fractions in WPI
% of Total Protein
icrofiltered Ion-exchange
Beta-Lactoglobulin 50 80
Alpha-Lactalbumin 22 14
Bovine Serum Albumin 2 3
Immunoglobulins 5 3
Glycomacropeptide 25 0
Several different technologies have been used to concentrate the protein in whey and remove fat, but the two that are currently used commercially are ion-exchange and microfiltration. The resulting whey protein isolates (WPI’s) are at least 90 percent protein, are essentially fat-free, and contain little or no lactose as well. Their whipping, gelling and similar functional properties are very much like egg white.
There are two basic methods for manufacturing whey protein isolate, ion-exchange and microfiltration.
In the most commonly used ion-exchange process, the whey is acidified to the point that most of the proteins have a net positive charge. The whey is then mixed with a resin, similar to that used for water softening, which has a negative charge. The positively charged proteins bind to the resin, allowing everything else to pass through. After the unbound materials (mostly fat and lactose) are washed out of the resin bed, the pH is increased to release the bound proteins, which are then concentrated by ultrafiltration and spray dried.
WPI prepared by ion-exchange normally contains the full complement of -lactoglobulin, the principal whey protein; but much of the -lactalbumin and some of the immunoglobulins and other protein components are lost. The changes in the amounts of individual whey proteins in ion-exchange WPI may have an effect on desired nutritional or “nutraceutical” value which must be determined on a case-by-case basis.
In the microfiltration process, fat is removed from whey by the use of special membranes that allow the proteins and other soluble components to pass through while retaining the fat globules. The lactose and soluble minerals are then removed by ultrafiltration and diafiltration. Unlike ion-exchange, the microfiltration process allows the whey proteins to be recovered in their natural proportions in the final product.
At equivalent protein contents, microfiltered WPI tends to be lower in fat content, while ion-exchange WPI tends to be lower in lactose. It may be of particular interest that glycomacropeptide (GMP), a product of the cheesemaking process, is not usually retained in whey protein isolates prepared by ion-exchange, but GMP comprises approximately 25% of the whey proteins retained during microfiltration. GMP is nutritious for the body, as it helps control gastrointestinal diseases.
Typical Concentrations of Whey Protein Fractions in WPI
% of Total Protein
icrofiltered Ion-exchange
Beta-Lactoglobulin 50 80
Alpha-Lactalbumin 22 14
Bovine Serum Albumin 2 3
Immunoglobulins 5 3
Glycomacropeptide 25 0