Ion Exchange vs. Cross-Flow Microfiltration
So, by now, you know you want whey, and you've probably realized that an isolate will work best for you. But, as a savvy consumer, you should also be aware that not all isolates are created equal. Different processing techniques among whey protein isolates result in surprisingly varied protein profiles.

Two isolate processing techniques are ion exchange and cross-flow microfiltration.

Ion Exchange
It yields the highest protein levels of any whey processing method (on a gram-for-gram basis), but don't be fooled. Ion-exchange isolates, like many concentrates, have sacrificed biological activity for quantity.

Ion-exchange isolates are made by running concentrates through what is called an ion exchange column, which separates proteins based on their electrical charge. During this process, many valuable and health-promoting components of whey are selectively depleted or completely lost. (15) One of these is glycomacropeptide, or GMP. (16) In its place, ion-exchange isolates give you an increased concentration of the protein subfraction beta-Lactoglobulin (beta-Lac) - known as whey's least interesting and most allergenic subfraction. (17)

Cross-Flow Microfiltration
In direct contrast to ion exchange, cross-flow microfiltration produces the highest level of undenatured protein available among WPIs. It's a delicate process which comes quite close to the protein concentration levels of ion exchange, while keeping the valuable "extras" that ion exchange discards.

Instead of using destructive chemicals, cross-flow microfiltration uses filters to separate protein from undesirable fat, cholesterol and lactose, based on molecular size and shape.(18) The low-temperature process isolates the native protein of whey at its biologically natural pH, carefully preserving its biological activity. GMPs and other immune-boosting components remain in tact.

Whereas ion exchange keeps only some of whey's biologically active components, cross-flow microfiltration sustains a more complete protein profile-one of optimal balance, as found naturally in whey. There are virtually no denatured proteins, a superior amino acid profile, more calcium and less sodium. WPIs derived from cross-flow microfiltration are widely advocated as the very best source of whey protein.
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(15) Brink, Will. "The Whey to Go." FITNESS Rx Feb.2004: 176.
(16) Yang, Jim. "Whey Protein Processing Methods." Bodybuilding for You . Oct. 25, 2004 www.bodybuildingforyou.com/protein/whey-protein-processing.htm
(17) Brink, Will. "The Whey to Go." FITNESS Rx Feb.2004: 176.
(18) Yang, Jim. "Whey Protein Processing Methods." Bodybuilding for You . Oct. 25, 2004 www.bodybuildingforyou.com/protein/whey-protein-processing.htm