The challenges and opportunities of membrane processes in the protein shift

Membrane technology has revolutionized protein recovery in the food industry, beginning with whey protein extraction via ultrafiltration. This success led to its application in concentrating animal proteins like blood plasma, fish proteins, and albumen. As the protein shift towards plant-based sources grows, membrane processes now enable the industrial recovery of wheat, sunflower, and rapeseed proteins. Our research focuses on optimizing rapeseed protein recovery in South Sweden, using microfiltration for particle removal and ultrafiltration for concentration. Fouling and cleaning were analyzed with X-ray microtomography. This presentation explores membrane technology’s role in sustainable protein production from both animal and plant sources.Keywords: Food applications; Membrane processes; Animal proteins; Plant-based proteins;IntroductionProteins are vital to human health and a key part of modern food systems. With growing concerns about the environmental impact of meat and dairy, the food industry is shifting to-ward more sustainable protein sources. This “protein transition” is stimulated by consumer demand, regulations, and the availability of high-quality plant-based options. Although ani-mal proteins still dominate, plant-based protein consumption is rising, due to their lower car-bon and water footprints. The global protein market, currently worth over USD 30.7 billion, is projected to reach USD 47.4 billion by 2032, largely driven by alternative sources (Shahbandeh, 2025)Protein production often begins with dilute streams that must be concentrated to be economically viable. Concentration reduces downstream volume, energy use, and improves efficiency. Traditional methods like evaporation and spray drying are energy-intensive and can de-grade heat-sensitive proteins. Membrane separation, especially ultrafiltration (UF), offers a low-energy, gentle alternative that maintains protein integrity. Membranes also provide modularity, scalability, and continuous operation, making them ideal for evolving protein processes.Membrane applications for animal proteinsThe dairy industry pioneered membrane use in the 1960s–70s, especially for valorising whey from cheese production. Membranes enabled the separation of whey into protein-rich concentrates (WPCs) and isolates (WPIs). Today, dairy processors use microfiltration (MF), UF, nanofiltration (NF), and reverse osmosis (RO) in tailored combinations: MF removes bacteria and fat, UF retains proteins, NF demineralizes, and RO removes water. This success laid the groundwork for membranes in other animal protein applications.Egg whites are another example. Their heat-sensitive properties require gentle processing. Membrane methods, particularly RO and UF, allow low-temperature water removal while preserving functionality. RO reduces water content first, followed by UF for protein concentration. These steps are often performed in staged, batch or semi-continuous systems. Alternating alkaline and acid cleaning cycles help control fouling and maintain performance, sup-porting both quality and efficiency.Membrane applications for plant-based proteinsThough still emerging, membrane use in plant-based proteins is promising. Similar to dairy, MF removes solids, UF concentrates proteins, and NF recycles salts and water. However, plant streams are often more complex and prone to fouling. Protein extraction may involve pH shifts or salts. UF can recover proteins, recycle water, and reduce chemical needs. For instance, globulins can be precipitated, while albumins in the supernatant are recovered via UF. NF may follow to recover solutes and purify streams.One studied plant source at Lund University is rapeseed protein. While mainly grown for oil, rapeseed’s press cake contains proteins limited by taste and anti-nutrients. Membrane filtration is being explored to overcome these issues. In a recent study, Swedish rapeseed press cake was milled and water-extracted, then filtered. MF (0.1–0.2 µm) showed high retention but low flux, while 15 kDa UF membranes concentrated proteins to 80 g/L with 55% purity. However, fouling was significant—microtomography revealed dense cake layers. Alkaline cleaning helped restore flux, though some fouling persisted. This underscores both potential and challenges in non-dairy applications.Outlook and conclusionsDespite success, membrane systems face hurdles like fouling, cleaning, and feed variability. Each protein stream demands tailored membrane selection and process design. Longevity, cleaning frequency, and product quality all affect cost and feasibility. Innovations in mem-brane materials, modules, and hybrid processes are addressing these issues. Pairing with electrodialysis, forward osmosis, or membrane distillation can boost performance and water recovery. Pre-treatments like enzymatic or pH adjustments also help minimize fouling and enhance yields.From their dairy origins to emerging plant applications, membranes are pivotal in sustainable protein processing. As the industry expands to sources like hemp, quinoa, algae, fungi, and precision fermentation, membrane systems will continue to evolve. Their ability to concentrate and purify under mild conditions ensures they remain vital to the global protein transition. The future of food depends not just on new proteins—but on the technologies that make them viable.AcknowledgementsThe authors acknowledge funding from the Swedish Energy Agency Project number: P2022-00101 (Verification of membrane technology for plant-based dairies).ReferencesM. Shahbandeh, Global animal and plant-based protein market size 2021-2032, 2025, https://www.statista.com/statistics/1177892/global-plant-based-protein-market-value/ (checked 2025-04-30)