Operating flux during milk concentration is primarily shaped by the gel layer – the dynamic barrier that naturally forms on the membrane surface as product is concentrated. This gel layer develops because protein, fat, and other retained solids accumulate on the membrane, creating resistance to permeation. As total solids increase throughout the system, the gel layer becomes thicker, and operating flux declines. This is why flux is much lower at the “back end” of a milk concentration system than at the front.
During milk concentration with UF membranes, protein and fat are the main contributors to this gel layer. As these components accumulate on the membrane surface, they add resistance to permeation. As solids rise throughout the run, the gel layer becomes thicker and denser, leading to lower operating flux.
With conventional UF membranes, fat, protein, and other organic materials adhere directly to the membrane surface. This adhesion is the reason processors rely on multi-step cleaning programs to remove organic buildup and restore performance. The membrane surface holds onto these components, and significant chemical and mechanical effort is required to remove them.
Evolution membranes fundamentally change this behavior.
Resisting Gel Layer Formation
The gel layer that forms on ZwitterCo Evolution membranes is different because their zwitterionic chemistry is inherently hydrophilic or “water loving”. The membrane surface attracts water, creating a hydration layer that prevents proteins, fat, and other organic compounds from adhering during milk concentration.
This matters because when organic materials don’t adhere strongly, they are far easier to sweep away during operation. As a result, the gel layer that forms on Evolution membranes is thinner and offers less resistance to flow – even as solids increase.
Higher Sustainable Average Flux
A thinner gel layer means less resistance to permeance. That translates directly to a higher sustainable average flux during milk concentration.
By resisting the adhesion of organic solids, Evolution membranes:
- Maintain a thinner gel layer as solids increase, because protein and fat don’t adhere the same way on Evolution membranes.
- Require less effort to remove buildup, thanks to the hydrophilic zwitterionic surface.
- Deliver higher operating flux due to reduced resistance from the gel layer.
- Hold more consistent flux at higher solids because the gel layer stays thinner than on conventional membranes.
This is why processors observe higher flux with Evolution membranes when concentrating milk and other protein-rich products: the membrane surface stays cleaner for longer, the gel layer stays thinner, and resistance to flow stays lower.
Why Cleaning Programs Become Shorter and Lower-Cost
Because proteins, fats, and other organics do not adhere to Evolution membranes in the same way they do with conventional UF membranes, cleaning programs can be simplified with one or more wash steps removed. Traditional UF relies on lengthy, multi-step cleaning because the membrane surface binds organic material tightly.
Evolution membranes do not require that level of intervention. Their performance may be fully restored with a shorter, lower-cost cleaning program because foulants do not bind as firmly and are easier to remove.
This delivers clear, measurable operational benefits:
- Less downtime required for cleaning
- Lower chemical costs
- Reduced water use and wastewater generation
- Lower energy requirements
- More predictable day-to-day operations
Since cleaning is a daily activity in milk concentration, these gains directly increase overall productivity.
A New Standard for Milk Concentration with UF Membranes
The gel layer has always dictated flux in UF-based milk concentration. Conventional membranes allow proteins and fats to adhere, create a thicker barrier layer, and require intensive cleaning to keep performance stable.
ZwitterCo Evolution membranes reshape that entire dynamic. By resisting adhesion, they keep the gel layer thinner, enable higher sustainable flux, and recover performance with shorter, lower-cost cleaning programs.
Looking to improve membrane productivity and performance in milk concentration? Reach out today to learn whether Evolution membranes are a fit for your process.