Sweet whey powder (henceforth "SWP") is a byproduct of making cheese and is a commodity.

The protein content of SWP is 13.1% protein by weight. The rest of it is largely sugar (74.5%). See its nutrition fact sheet here.

One can buy SWP at $50 for 55 pounds from a bulk foods co-op, like Azure Standard, and thus the price per pound of protein would be:

 $50           1 unit SWP            $6.94
------ * --------------------  = -------------
55 lbs    0.131 units protein    1 lbs protein

Conversely, for whey concentrate:

$96.48     30.4g WC         $12.22
------ * ------------ = -------------
10 lbs   24 g protein   1 lbs protein

I did the analysis for simple whole milk, but I've forgotten the price per gallon. The number my wife gave me last night yielded a higher price per pound of protein than using the SWP:

   $???           gallon      453.5g      $????
----------- * ------------  * ------- = -------------
Gallon Milk   128 g protein    1 lbs     1 lbs protein

All that said, the price per pound of protein of SWP is about half that of whey concentrate.

Previously I have fermented out the lactose with kefir grains, but it was disgusting. If I must have a lactic acid in the output, I'd like the concentration to be yogurt-level or less.

Is there an easy, at-home method to separate the protein from sweet whey powder?

  • Even if you could separate the protein from the sugars, what would you do with it? – SAJ14SAJ Jun 22 '13 at 20:54
  • Half-price whey protein for adding to smoothies in support of weightlifting is a very tantalizing prospect :-) – Ross Rogers Jun 23 '13 at 19:37
  • Where I live, hamburger is cheaper than both of those prices, even the very lean stuff. – SAJ14SAJ Jun 23 '13 at 19:41
  • There is a convenience factor to whey powder. I have a smoothie for breakfast mostly and that's what I'd like to add it to. – Ross Rogers Jun 23 '13 at 19:43
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    Isoelectric precipitation of casein might well work with sweet whey. Here's a truly awful video to give you the idea: youtube.com/watch?v=UAjNsMtiLqo short form: Add 1/8th vol vinegar, wait, collect the precipitate. – Wayfaring Stranger Oct 29 '15 at 18:53

While it is not possible to conclusively say something cannot be done—and perhaps someone will come along who can offer additional insight—I don't think it is practical to separate the protein from sweet whey powder at home.

It is highly likely that the reason the concentrated protein is considerably more expensive per unit weight is because it is difficult and energy intensive to separate from the whey, and doing so requires expensive capital equipment that must be paid for.

In researching how this is done, I found the following sources:

See this transcript from NPR, which explains the industrial process required to separate the protein from the sugars in whey. It involves industrial type filters, and considerable equipment. Admittedly, some of that is due to the scale of the plant which would not apply at home, but the process is only feasible due to the scale of the plant.

According to NIH, a centrifuge is nearly always required, which is not typical home equipment:

The first step in a typical protein-purification scheme is centrifugation. The principle behind centrifugation is that two particles in suspension (cells, organelles, or molecules), having different masses or densities will settle to the bottom of a tube at different rates. Remember, mass is the weight of a sample (measured in grams), whereas density is the ratio of its weight to volume (grams/liter). Proteins vary greatly in mass but not in density. The average density of a protein is 1.37 g/cm3. Unless a protein has an attached lipid or carbohydrate, its density will not vary by more than 15 percent from this value.

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  • That is an excellent overview. Thank you. I have a relative in R&D for water filtration, so I'll talk to him about what it would take to get an appropriately-sized filter to strain out the whey protein. Hopefully I'll have good new to post back here. – Ross Rogers Jun 23 '13 at 19:42

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