Whey protein is one of the two major groups of proteins found in milk and is a by-product of cheese-making. This whey by-product is in liquid form and is known as raw whey. Raw whey is composed of naturally occurring macronutrients – protein, fat, minerals, lactose and water as well as micronutrients that are biologically active – alpha lactalbumin, beta lactalbumin, lactoferrin, glycomacropeptides, igG and peptoaminoacids.
There are two main methods used to separate whey protein: membrane filtration and ion exchange. We will start with the latter ion exchange which, in terms of nutrition, is our proverbial spider.
Ion exchange whey protein
Ion exchange is a chemical method that utilizes pH adjustment in order to achieve protein separation. Raw whey is sent through a column that has an affinity for protein. The protein is collected and all the other macronutrients pass through. Chemical reagents sodium hydroxide and hydrochloric acid are introduced in order to release the protein, by adjusting the pH.
While this yields a very high protein ingredient – 90-96%, with no fat or carbs (lactose), this pH adjustment can denature the protein and can reduce the biological activity of the protein and it’s micronutrients. Reduced or eliminated are antioxidants, essential amino acids, protein digestion, calcium absorption and immune support to name a few. The total carb savings in ion exchange is 6-10g; the same amount found in nutrient powerhouses almonds and spinach respectively. Lastly, due to the protein denaturing, ion exchange has noticeable flavor differences. Ion exchange protein tastes processed; salty with less dairy notes.
Manufacturers alter the acidity or alkalinity (pH) of the solution to remove impurities and undesired materials. Synthetic resins are commonly used for ion exchange during the water purification process but it also occurs naturally in the Earth’s soil and living cells.
Manufacturers turn the surface charge attraction between the desired protein molecules and ion exchange resin on and off to isolate the desired elements. When an excess amount of undesired materials build up in the machine it’s cleaned and the ion exchange process resumes.
Ion exchange offers the benefit of increased selectively in what is and is not filtered compared to cold-filtered whey protein. While ion exchange yields some of the highest concentrations protein per serving, there are a number concerns around using this filtration process. While it does increase protein concentration it decreases the subfraction glycomacropeptide (GMP) and increases the subfraction ß-lactoglobulin.
While this may not sound like a concern GMP appears to offer numerous immune-protecting benefits while ß-lactoglobulin has been identified as the subfraction in milk causing the most allergic reactions in humans.
Ion exchange filtration also uses strong acids and bases to adjust pH levels and resulting charge affinity. While the pH doesn’t significantly change it’s worth noting that it temporarily alters the structure of the protein. Since ion exchange resins do not act as filters they do not remove bacteria or other microorganisms.
If the resin is not cleaned or replaced regularly then serious contamination issues may occur.
Membrane filtration whey protein
UF is used extensively in the dairy industry; particularly in the processing of cheese whey to obtain whey protein concentrate (WPC) and lactose-rich permeate. In a single stage, a UF process is able to concentrate the whey 10-30 times the feed.
Membrane filtration is a cold temperature processing method that allows for the production of a high protein finished whey where the protein remains intact (undenatured) and is not treated with chemical reagents. Membrane filtration uses a filter with different pore sizes which allows carbohydrates and minerals in raw whey to pass through and retain the whey protein.
While concentrating the proteins membrane filtration does not change the protein profile of naturally occurring whey proteins, where as ion exchange changes the protein profile and selectively takes away the more beneficial bioactives like alphalactalbumin and other components, which are the most valuable components of whey and have functions like stress relieving, faster recovery and immune development. Membrane filtration is century long technology that is similar to the one used in water filtration at home and works by size exclusion to retain those valuable components of whey.
Membrane filtration yields a high protein product with a small amount of naturally occurring fat, lactose and minerals, for which the micronutrients are biologically active. Membrane filtration whey tastes as it should, clean with pleasant, native dairy notes.
The original alternative to membrane filtration of whey was using steam heating followed by drum drying or spray drying. The product of these methods had limited applications due to its granulated texture and insolubility. Existing methods also had inconsistent product composition, high capital and operating costs and due to the excessive heat used in drying would often denature some of the proteins.
Compared to traditional methods, UF processes used for this application
Are more energy efficient
Have consistent product quality, 35-80% protein product depending on operating conditions
Do not denature proteins as they use moderate operating conditions
The potential for fouling is widely discussed, being identified as a significant contributor to decline in productivity. Cheese whey contains high concentrations of calcium phosphate which can potentially lead to scale deposits on the membrane surface. As a result substantial pretreatment must be implemented to balance pH and temperature of the feed to maintain solubility of calcium salts.
Which process is best for whey protein?
Membrane filtration and ion exchange yield nutritional differences in their finished ingredients, and for anyone paying a pretty penny for whey protein and their health and fitness, we think that membrane filtration is the superior product. The extremely low carbs in ion exchange protein may not be worth losing the bioactivity of whey protein and it’s micronutrients.
P.S. For Old School Protein products we only use membrane filtered whey so that we can assure our customers get only the best quality.