Choosing a Whey Protein

Since I eat this stuff every day, and really had no idea how to choose between the many varieties, I thought I would do a little research.  Let me start by saying that I am no expert in whey, I only thought that I might save some other regular guys and gals like myself some time by relaying what I have found in a few hours research online.

First off, what is whey? Whey is a byproduct of the cheese making process.  Cheese is made from milk. Milk has two types of proteins, casein and whey.  In order to make cheese these two are separated as follows. Bacterial cultures are added to milk, this produces acidity and makes the milk more receptive to an enzyme that will be added next.  This enzyme, called rennin, converts one of the milk proteins (casein) into an insoluble form.  Since the casein is no longer soluble it condenses out into cheese blobs, called curd.  The liquid that is left is the whey.  So from milk, cultures, and enzymes we now have curds and whey! If you think that's exciting, I'm only getting started!  Oh yeah, and I will try to fight the urge to insert a picture of Little Miss Muffet... no promises. 

Ok, so now we can separate the whey, which is the liquid in the picture above.  But what is actually in it?  Well, the whey is composed of protein, lactose, fat and a variety of minerals.  The protein is made of smaller fragments called subfractions which each exhibit their own biological activity in the body.  Some may help with immunity, such as lactoferrin.  Others are thought to be beneficial in a multitude of ways, such as lowering blood pressure, improving performance, reducing cortisol levels, and so on.  I will not go into depth here because I don't want to bore anybody to death.  But, for those who want more on that, check out an article called "The Whey It Is" at brinkzone.com, its written well and the guy seems to know his stuff.
The next thing we will look at is how the whey is processed once it has been separated from the curds, and how these processes affect the quality of the protein product produced. Say that five times fast!

After separation, the whey is filtered.  The product of the first pass is called a concentrate, it can retain from about 30-80% protein, and still contains a fair amount of fat and lactose.  Though some concentrates have protein percentages on the low end, the ones used in supplements that you would buy in the store are normally 70 to 80%.  The product from the second filtration is called an isolate, and contains a higher percent of protein, about 90.  Isolates have virtually no fat or lactose, which can make them a good choice for those who are afflicted with a lactose intolerance.

So it seems that the isolate may be the way to go, based solely on protein concentration.  But there is another thing to consider.  Low temperatures and stable pH conditions should be maintained during the process or the protein may become severely denatured. If this occurs during the refining process, it can render the amino acids less digestible and generate potentially carcinogenic nitrogen compounds.

Two main processes are used to attain the supplements we see on the shelf today.  Ion exchange, and cross flow microfiltration.  Ion exchange does yield the highest protein content and a product essentially free of lactose.  But in the same way it reduces lactose, it in turn gets rid of most of the beneficial subfractions.  Also, the acids used in the ion exchange process can damage the protein and make it less valuable for digestion.  Cross flow microfiltration, on the other hand, involves lower temperatures and a more stable pH. This results in a higher quality product which retains high amounts of subfractions, and supplies a protein concentration that is not significantly lower than that of ion exchange.  You will see cross flow microfiltration products referred to as isolates based on concentration.  The only true down side I see to cross flow microfiltration is that is does leave some fat and lactose in the product.
Whew! That was a mouthful, but at least now I have some vague idea of what that magical white powder I've been eating is. Hope this was a useful read.  Let me reiterate that I am no expert, but I did try to find reliable sources and I'm certainly open to any useful comments anybody has.
This info came from www.brinkzone.com, www.whey-proteinguide.com, biology.clc.uc.edu/fankhauser/Cheese/Cheese_course, and wheyoflife.org

 Also, the best tasting protein I have found is Jay Robb, don't be scared of the dude on the package, it's good stuff.