Cross Flow Micro Filtration – Don’t Believe The Hype

There is a lot of terminology out there in the protein powder supplements industry; scientific names that sound really good but you have no idea what they actually mean like cross flow micro filtered and ultra filtration. Well, today I would like to try and debunk some of these elevated terms and find out what it actually means for me and you who are taking protein powders.

First, though, we need to make sure that we are familiar with the different types of whey.

Types of Whey

There are three main types of whey protein that are used in most protein powders. There are others, like soy protein, but let’s just keep it simple for now.

  1. Whey Concentrate
  2. Whey Isolate
  3. Hydrolyzed Whey

How Proteins Powders are Made

The usual process is that the raw whey goes through some kind of filtration or cleansing process to remove unwanted parts of whey, like lactose, fats, cholesterol, sugars, etc. It’s these processes that differ and new methods are being developed all of the time.

Using the three protein types above we can generalise and say something about each one of them:

Whey Concentrate – Considered the purest because it has gone through the least amount of processing, but on the downside contains the most amount of unwanted substances like lactose. Usually cheapest as a result of less processing and the quality of the supplement is not considered as high.

Whey Isolate – Has usually been processed more intensively than a concentrate, reducing the amounts of unwanted substances. This increases cost but yields a much higher protein concentration. Depending on the filtration processed used, there may be damage to the proteins caused by heat – see ion exchange section below.

Hydrolyzed Whey – This is whey protein which has been partially digested with the aim that it can improve the absorption rate into the bloodstream and therefore to the muscles. This requires even more processing than the whey isolate, but increases the protein content percentage and removes nearly all unwanted substances, like lactose, carbohydrates and fats. This type of protein is the most expensive yet (usually) contains the least amount of unwanted substances.

Protein Filtration

The next question you are probably asking is: “How are the proteins filtered and processed?” And the answer to that is what I shall write about next.

Normal Flow Filtration (NFF) which is also known as “dean-end” filtration, is something you’re probably already familiar with. In short, it’s a filter that is used to remove/trap unwanted particles whilst allowing the smaller, wanted particles through. It’s just a standard filter like when you use a sieve for gold, albeit working on a much smaller particle level.

Cross Flow Filtration (CFF) is similar, but different. The flow (feed) is running alongside the filter with a little pressure is being applied to push the mixture against the filter. Here is a diagram to help explain both normal and cross flow filtration:

Protein Filtration

CFF is just a different way of achieving the same goal, which in the case of protein powder is to remove certain parts of the mixture and keep others. One immediately obvious advantage is that with CFF the particles are going to get many chances to be filtered as they move along the filter and the filter will not become blocked as easily when compared to the NFF process.

Micro Filtration

Micro Filtration is part of the CFF process. It is called Micro Filtration because of the size of the particles that the filter is filtering out. It usually removes intact cells and debris from a mixture, so it’s like a first stage of filtering.

Ultra Filtration

Ultra Filtration is again part of the CFF process. The name comes from the fact that at this stage the particles being filtered out are much smaller. So this is just another filtering process but further down the line compared to Micro Filtration.

Note: Ion Exchange is a filtration process which generally means to purify, separate or decontaminate a water based mixture. In terms of protein powders this process uses heat to achieve the filtering which may damage the proteins.

What Does it all Mean?

Well, we can say that Cross Flow Micro Filtration is just a processing method to remove unwanted particles from a protein mixture. We can say the same about Micro Filtration and Ultra Filtration, as these do the same thing just at a different size of particle filtration.

You’ll find that a lot of protein manufacturers put all these kinds of claims on their packaging to make it sound very high-tech and like it’s the latest thing to the industry but in reality it just means that the protein powder has been filtered using different sized filters. Exactly what you would expect, really. The more unwanted substances that have been removed, the more filtering has been done and it costs more to do it.

I should point out that at the moment it is difficult to know at what temperatures the processes have been carried out at. From my research so far it seems that cross flow filtration is done at lower temperatures resulting in less chance of the proteins becoming damaged. If the filtering processes are completed at higher temperatures it can damage the proteins, similar to how a microwave would be thought to damage the quality of the food.


I would try to avoid the ion exchange method because the use of heat may cause damage to the proteins which neutralises their effectiveness. I’d also tend to stick with protein powders that state the processing is done at low temperatures to reduce potentially damaging the protein powder’s potency.