How Should Membrane Systems Be Combined for Low-Lactose and High-Protein Dairy Products?

The demand for low-lactose, high-protein, low-salt, and concentrated dairy products continues to grow. However, these products are not simply created by “adding more protein and reducing sugar content.”

Behind these products lies a series of separation processes: retaining proteins, removing lactose, salts, and part of the water, while maintaining product flavor, nutritional value, and processing performance as much as possible.

For dairy processors, the key questions are:

What product do we want to produce? Which components should be retained, and which components should pass through the membrane?

1. High-Protein and Low-Lactose Products Require Two Objectives to Be Achieved Simultaneously

High-protein products require increasing protein concentration, while low-lactose products require reducing lactose content.

If only simple concentration is applied, proteins, lactose, and salts may all increase together, making it difficult to achieve the desired product characteristics. Therefore, it is necessary to perform step-by-step separation based on differences in particle size and molecular weight among different components.

According to Jiuwu’s dairy industry livestream materials, Jiuwu provides a range of membrane technologies, including ceramic microfiltration, ceramic ultrafiltration, polymeric ultrafiltration, nanofiltration, and reverse osmosis. These technologies are applied respectively for sterilization, protein separation, lactose and salt removal, and dehydration/concentration processes.

2. Step One: Determine Whether Physical Sterilization Is Required Based on Product Requirements

For dairy streams that will undergo further protein separation and purification, upstream treatment can significantly affect subsequent processes.

Jiuwu’s 1.4 μm ceramic membrane for dairy sterilization uses a physical separation approach, primarily to retain microorganisms in the feed stream while allowing components such as milk proteins and lactose to pass through.

This approach does not require the addition of external substances such as filter aids and can also reduce the impact of high-temperature treatment on protein structure and subsequent separation performance.

However, not every project requires this step. Whether physical sterilization should be applied should be determined based on the raw material hygiene conditions, downstream products, and production requirements.

3. Step Two: When Whey Protein Is Required, Separate Casein First

The main proteins in raw milk are casein and whey protein, which have different application values.

Jiuwu’s 0.1 μm ceramic membrane utilizes the particle size difference between the two types of proteins to:

●  Retain casein;

●  Allow whey protein to pass through into the permeate stream;

●  Further carry out subsequent concentration and purification processes separately.

Through this step, dairy processors can further produce casein powder, whey protein, and related dairy protein ingredients, improving the utilization efficiency of high-value components in raw milk.

If the target product does not require separation of the two protein fractions, this step can be skipped, and the process can proceed directly to subsequent concentration or formulation.

4. Step Three: Use Ultrafiltration for Protein Retention and Lactose Permeation

The key step in producing low-lactose and high-protein dairy products is using the membrane’s molecular weight cut-off capability to retain milk proteins while allowing lactose, salts, and some small molecular components to pass through.

The 10 kDa membrane introduced in the livestream materials is mainly used for:

●  Retaining whey protein and other high-molecular-weight components;

●  Allowing small molecular components such as lactose and salts to pass through;

●  Achieving protein concentration and preliminary lactose and salt removal.

This step can be applied in the production of whey protein, Greek yogurt, concentrated milk, and other high-protein dairy products.

In practical projects, factors such as target protein concentration, residual lactose requirements, membrane flux, and product yield must also be considered. The process design cannot be determined solely based on membrane specifications.

5. Step Four: Use Nanofiltration and Reverse Osmosis for Fine Adjustment

If the product requires stricter control of lactose or salt content, nanofiltration can be further applied for fine separation.

Nanofiltration is mainly used for desalination and the separation of lactose and other small molecular components. Reverse osmosis is primarily used for water removal, increasing feed concentration, and reducing the load on subsequent evaporation processes.

This can form a basic process concept:

Physical sterilization → Protein fractionation → Ultrafiltration concentration → Nanofiltration for lactose and salt removal → Reverse osmosis dehydration

This represents a technical approach rather than a requirement that every project must include all process steps. Customers should select the appropriate process combination based on their target products and production requirements.

6. Jiuwu’s Advantage: Considering the Application Boundaries of Different Membrane Technologies

Jiuwu offers a comprehensive range of membrane products, including ceramic membranes as well as polymeric UF, NF, and RO membranes. The company also provides capabilities in process design, equipment manufacturing, and integrated solutions.

According to Jiuwu’s corporate materials, its food and beverage solutions cover multiple processes, including filtration and sterilization, fractionation, desalination, and concentration. Membrane separation processes feature room-temperature operation, no phase change, and no need for filter aids, which helps preserve the flavor of heat-sensitive products and improve product yield.

For customers, this means that membrane selection does not need to be limited in advance to “ceramic membranes only” or “polymeric membranes only.” Instead, the optimal combination should be selected based on raw material characteristics, product specifications, and lifecycle costs.

When developing low-lactose and high-protein products, it is recommended to first clarify the following four aspects:

Raw material type, target protein content, target lactose content, and planned processing capacity.

With these basic data, it becomes possible to further determine which membrane processes are required and what role each process step should perform.