There are two starting paths for capturing dairy proteins from existing product streams in dairy processing plants. The first is to process cheese-based whey for whey protein concentrate (WPC). The second is to process skim milk for milk protein concentrate (MPC).
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In order to get to WPC-80, raw milk must first go through the cheesemaking process to separate out the liquid sweet whey (Diagram 1). The whey is then clarified to remove any remaining fat. Next, a filtration step captures the whey permeate, separating that from the protein. The protein is then spray dried to produce the WPC-80.
Diagram 1.
MPC processing is a bit simpler. The milk is separated into skim milk and butterfat. The skim milk is next put through a filtration step, resulting in milk permeate and protein. The protein is then spray dried to create the MPC-80 powder.
In both of these examples the “80” signifies 80% protein in the final powdered product. Milk protein concentrates can be taken to 60, 70 or 80 percent protein levels. Milk protein isolates can even achieve 90-92 percent protein concentration. There is more flexibility for these ingredients based on what the end user wants to accomplish with the protein.
Here is a mass balance illustrating what happens with 1,000,000 lbs of raw milk feed at 12% total solids (TS) being processed into WPC-80 powder. This is a broad overview for illustration purposes — the values you are working with may vary.
Membrane filtration is a key step in processing the whey stream. This is where the protein is concentrated while smaller components pass through. The retentate stream that results is what holds the valuable protein. There is also the permeate stream that must be dealt with. While not insubstantial, the high value of the whey protein stream should be enough to provide options for dealing with the permeate stream.
Due to the high solids in the resulting retentate, there usually isn’t a need for an evaporation step before moving the feed to a spray dryer.
Diafiltration incorporates more water into the stream before the filtration step. This additional water is part of the reason there is a hefty amount of permeate to deal with, but it is a necessary part of the process. Higher concentrations will mean higher water usage and more complicated downstream handling requirements.
This next diagram follows the feed from the filtration step to the spray drying step.
In Part 3 of this series, we’ll cover operations and strategy considerations for new entrants into the dairy proteins space. If you have questions in the meantime, give us a call. Dial 410-822-6900 or email problem.solved@caloris.com.
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