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.
What if you fermented out the sugar from the SWP using a kefir process? How long would it take to ferment most of the lactose out? How much sugar would remain? Chris Kresser quotes that kefir fermented from milk nukes all the lactose in about 2 days.
What might be some of the problems with this process? How is my analysis invalid?
I understand you'd lose some of the flexibility of the dry powder, as you'd have to reconstitute the SWP and then let it ferment for a few days.
asked byRoss_Rogers (20)
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on October 28, 2012
at 10:07 PM
So, I tried this. The upshot is that it tastes waay too sour. I tried water with sweet whey powder (SWP) and I tried 1 part milk with one part SWP and they both taste very sour. I like sour in normal kefir, sauerkraut, fermented veggies, et c. This was too much for me. I couldn't do this regularly.
on August 24, 2012
at 05:36 PM
Ross, I think your numbers are fairly accurate. If you have the time and effort, then go forth. For me, the effort skews the cost/benefit ratio. I wonder whether the absorption of SWP would be closer to whey concentrate or isolate? That might also skew it...