The degree of denaturation is normally expressed by the Whey Protein Nitrogen Index (WPNI), i.e. in milligrams of undenatured whey protein nitrogen per gram of powder. (dairyprocessinghandbook.com)
This bonded cysteine is also found in human breast milk, and can be replicated with raw cow's milk in the form of undenatured whey protein. (aminoacidstudies.org)
Undenatured whey protein powder boosts glutathione levels by converting cysteine into glutathione. (mindbodygreen.com)