Thankfully, the phrase “nutrient density” is something that has become relatively commonplace. For the sake of this article, It is effectively defined as the percentage of a macronutrient out of the total energy density.
If food is prepared differently, the nutrient density may vary.
A good example comparison would be:
Whole milk (full fat):
150 total kcal
8g protein — ~21% protein
Skimmed milk (fat free):
90 total kcal
9g protein — ~40% protein
The point is that different methods of prepping foods (both commercially and household) would change the nutrient density one way or the other. It is possible to prepare the milk to separate the proteins from the other fats and sugar.
If milk is acidified, then the casein protein will coagulate. When the protein coagulates it is easily separated from the remaining brother and one is left with the sugars and the delicious golden whey. From this stage the remaining solution can be filtered and further purified. The amount of filtration will determine the “quality” of the protein.
Whey that is purified into the range of 75-85% is considered a concentrate.
Whey that is purified into the range of 86+ % is considered an isolate.
There are several ways that the way can be filtered and purified and each of them has their own pros and cons.
The two most popular commercial methods for protein filtration/purification are as follows:
Microfiltration:
- Process: forcing whey solution through filtration membranes that have pore sizes in the 250 nanometer to 1 micrometer range. These pores are small enough to catch the whey proteins but large enough to let the sugars and fats through. Think “size exclusion”
- Advantage: Higher % of the whey protein is left in its native state, leaving the immune boosting/anticarcinogenic/ergogenic proteins and peptides intact.
- Disadvantage: Cost, not as feasible to get the best protein density.
Ion Exchange:
- Process: The protein is given a charge by being exposed to acid (+) and/or base (-). Once the protein is charged, it can then be incubated with a resin of the opposite charge and electrostatically bind the protein and separate it from the relatively inert fat and sugar molecules (think about sticking a magnet in sand and just pulling out all the magnetic iron from the silt). Each charge exchange can be considered a separate purification, and multi-step purifications are typically of the highest purity.
- Advantage: Cost, Highest Purity
- Disadvantage: Some bioactive proteins can be degraded due to chemical treatment.
Further Processing:
Protein, like any other polymerized macronutrient must be digested in a series of stages before the valuable amino acids can be utilized by our hungry cells.
- Mastication
- Pepsin and acid in the stomach
- Partial hydrolysis in the small intestine by peptidases (2-8 amino acid peptides)
- Full hydrolysis in the small intestine by peptidases (single amino acid residues)
Both small peptides (~4 amino acids) and free aminos can be (readily) absorbed through the small intestine into the bloodstream and be utilized.
Note: Small peptides, as they take specific transfer pathways through the gut, must still be broken down to free aminos before being incorporated into anabolic or catabolic pathways.
What if most of the protein digestion can be circumvented through the marvels of food science?
It has been and you’ve probably heard of it. The protein is broken down through the most common biochemical reaction around, hydrolysis. There are some products that expose protein to proteolytic enzymes effectively making the protein pre-digested. This has a plethora of implications I will cover in another article. Including quicker absorption than whole proteins or free aminos and interesting metabolic changes associated with hydrolyzed protein consumption.
However, further processing means further cost. Is the cost worth it?
When I review some of the recent literature in my next article, I’ll let you decide.
