Materials and system design

According to Shanti Bhushan, GEA Group principal process development engineer, advances in membrane materials and system design are significantly improving the efficiency and economics of lactose removal across a wide range of dairy processes. These include milk and whey protein concentrates, lactose-reduced and lactose-free milks, and fermented products like Greek yogurt, cream cheese and skyr.

Modern ultrafiltration and microfiltration membranes are increasingly engineered with hydrophilic surfaces and specialized polymer chemistries that reduce fouling and improve flux recovery. These improvements allow processors to operate systems for longer periods while maintaining higher throughput.

Bhushan notes that advances in polymer chemistry, including zwitterionic and charged membrane materials, as well as ceramic options, further enhance durability and separation performance across demanding dairy processes.

At the plant level, processors are also optimizing system design. Multistage diafiltration strategies, for example, allow lactose and minerals to move into the permeate stream while retaining proteins in the concentrate. This approach helps reduce water use while improving the recovery of valuable dairy solids.

Membrane configuration

Better control over protein retention is also delivering economic benefits. When membranes are properly selected and operated within the right pressure and concentration ranges, unintended protein losses to the permeate stream can be minimized. “By minimizing unintended protein passage to the permeate and tightening mass‑balance control, processors can consistently hit specification and lower waste,” Bhushan explains.

Membrane configuration is also evolving to support high-viscosity dairy streams. As products like Greek yogurt and skyr become more concentrated, viscosity rises sharply, which can reduce filtration efficiency if systems are not properly designed. To address this, many plants use hybrid configurations that combine spiral-wound membranes with plate-and-frame or tubular modules. Spiral-wound elements provide high membrane surface area during early stages when viscosity is low, while tubular systems can better handle thicker streams later in the process.

Even with these improvements, scaling lactose removal systems requires careful process control. Fouling and mineral management remain among the most common operational challenges, particularly when concentrating lactose-rich streams.

Bhushan explains that nanofiltration is frequently used downstream of ultrafiltration permeate streams to concentrate lactose while allowing certain salts to pass through the membrane. During this process, however, divalent minerals such as calcium and magnesium can accumulate alongside lactose, increasing risk of scaling.

“Mitigation relies on selecting NF membranes with suitable lactose rejection and ion selectivity, limiting maximum solids concentration and operating at cold temperatures,” Bhushan says. He notes that diafiltration can also help selectively recover sodium and potassium in the permeate while keeping hardness under control.

In some cases, processors may use small additions of processing aids such as citric acid or carbon dioxide to reduce mineral scaling and improve membrane cleanability. These strategies must be carefully validated, though, to ensure regulatory compliance and avoid unwanted impacts on flavor.

Process consistency and product quality

Process control is equally critical to maintain consistent lactose removal while protecting product quality. Operators must carefully monitor key metrics such as transmembrane pressure (TMP), temperature, solids concentration and conductivity throughout the system. “Tight TMP control during ultrafiltration and microfiltration prevents excessive fouling while maintaining high average flux,” Bhushan says. “Gradual increases signal concentration polarization, while sharp rises demand immediate clean-in-place intervention.”

Inline monitoring tools are becoming increasingly valuable for maintaining process stability. Technologies such as refractometers and near-infrared spectroscopy allow processors to track solids and protein concentrations in real time, improving mass balance control and helping operators maintain consistent product specifications, Bhushan says.

The impact of lactose removal extends beyond the filtration system itself. Adjusting lactose levels can affect downstream processes including fermentation, formulation and whey utilization. For example, direct enzymatic hydrolysis of lactose into glucose and galactose can significantly increase sweetness and accelerate Maillard browning reactions during high-heat processing.

Bhushan notes that, for this reason, many processors prefer partial lactose removal using membrane technologies to maintain a more balanced flavor profile. He states that partial lactose removal using membranes delivers a more milk-like sweetness balance while minimizing thermal damage and extending shelf life.

In cheese production, ultrafiltration enables processors to concentrate casein and whey proteins, improving protein recovery and overall yield. Microfiltration can also generate native whey streams that are valued for ingredient applications, Bhushan says.

Ultrafiltration also contributes to sustainability as permeates can serve as feedstocks for lactose crystallization or sweetener production, while microfiltration permeate streams free of rennet and fat are increasingly used in specialty and beverage applications across the industry.

These advances in membrane technology are reshaping how processors approach dairy ingredients. As processors continue expanding lactose-free product lines, membrane systems are playing a growing role in helping plants improve efficiency while recovering more value from milk components.