Skim Milk Powder - cheaper alternative to Whey?

Would skim milk powder be a good substitute for expensive whey protein powders?
Got talking about this yesterday with a couple of trainers and they pointed me to a study which showed that skim milk powder to be the best form of protein available on the market. I tried to search the study online and could not find any. Not sure who had funded the study. So tried to look up some info on skim milk powder.
 A standard skim milk powder has a nutritional label like this one here:

The breakdown of carbs:proteins:fats seems to be similar to some of the popular gainers on the market which contain high amounts of whey protein concentrate.

So is skim milk powder really the cheaper option and can it be safely used instead of whey?

Let's look at the money part first!

Skim milk powder has a protein content of about 35%, vs 85% for a whey protein concentrate.

SMP costs about $6.39/kg vs $29.95/kg for WPC

per gram protein, 

SMP costs 1.825 cents/gram (639 cents / 350g per kg)

vs 

WPC costs 3.52 cents /gram (2995 cents / 850g per kg)

For a 30g serving of protein,

SMP costs 54.75 cents

WPC costs 105.6 cents                                                                                  

2.What kind of protein does skim milk actually contain?

Let us look at this University of Illinois study:

"Centrifugation of the skim milk in an ultracentrifuge (usually about 50,000 x g or greater) results in pelleting of the casein and in a supernatant called whey (also sometimes called the serum phase of milk) which contains the water, lactose and soluble non-casein proteins. Once casein is removed, then by definition every other protein left in the milk preparation is a whey protein.

Casein molecules can also be separated from the whey by precipitation of the casein with acid (similar to what happens in the stomach when milk is consumed) or by disrupting the micellar structure by partial hydrolysis of the protein molecules with a proteolytic enzyme. In the stomach of the young of many species is an enzyme calledrennin which specifically hydrolyzes part of the casein micelle resulting in formation of a curd. A classic precipitation method for casein in cow milk which is done in the laboratory is to slowly add HCl (0.1 N) to lower the milk pH to 4.6. The casein will gradually form a precipitate while relatively little of the other milk proteins will precipitate. Different combinations of controlled acid precipitation and enzymatic hydrolysis of casein are the foundation of the cheese industries. Often specific bacterial cultures are used to establish the conditions for lowered pH and secretion of proteolytic enzymes which form the different types of cheese.

Because the casein micelle is in suspension, it can be separated from the rest of milk by centrifugation at a very high speed. Generally the milk is first defatted (the cream is removed) from whole milk by low speed centrifugation (at about 5,000 to 10,000 x g), resulting in the cream layer at the top, the aqueous supernatant, and a small pellet of leukocytes and other debris. The aqueous supernatant is the skim milk (sometimes called the plasma phase of milk). 

There are many whey proteins in milk and the specific set of whey proteins found in mammary secretions varies with the species, the stage of lactation, the presence of an intramammary infection, and other factors. The major whey proteins in cow milk are ß-lactoglobulin and a-lactalbumin. a-Lactalbumin is an important protein in the synthesis of lactose and its presence is central to the process of milk synthesis. ß-Lactoglobulin's function is not known. Other whey proteins are the immunoglobulins(antibodies; especially high in colostrum) and serum albumin (a serum protein). Whey proteins also include a long list of enzymes, hormones, growth factors, nutrient transporters, disease resistance factors, and others."In conclusion, we have established that skim milk powder is high in whey proteins.

So what is the problem?It is cheap and it has what we are looking for.
* SMP has a high amount of lactose and some people might find it intolerable to consume it 2 to 3 times a day. Also if you looking to use protein shakes to lose weight, SMP might not be the best option. Some bloggers have suggested to make a 50:50 mix with your whey protein gainers, but that is only for people who are looking to put on mass.


Sports Dietitians website lists SMP as an alternative source of protein:
Check out the recipe for their high energy drink.


http://www.sportsdietitians.com.au/resources/upload/file/Fact%20sheets/Protein%20for%20athletes.pdf


Hope this helps.