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Engineering R&D: Membranes and milk

February 1, 2011
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Separation technology helps researchers isolate components in milk, but understanding precisely what those components do remains an active area for research.

The line between food and pharmaceuticals is blurring as researchers investigate the interactions between food, nutrition and human health. Source: Institute of Nutraceuticals and Functional Foods.


Scientific understanding of the elements of food and how they interact with the human body remains in its infancy, and the more complex the food, the more research that is needed. This is especially true with milk, one of the most complex foods. Concerns over fat content and its role in cardiovascular disease put milk producers on the defensive in recent decades, though new studies suggest milk consumption may actually reduce the risk.

Besides identifying milk’s many components and their effects on health, cost-effective ways are needed to isolate and deliver them in the proper concentrations. Researchers are straddling the worlds of medicine and commercial food production as they apply filtration and membrane technology. Multidisciplinary collaboration is needed, and a number of organizations have been formed to foster it. Among them is the Institute of Nutraceuticals and Functional Foods (INAF), which was founded in 1999 on the campus of Laval University in Quebec, Canada. The American Dairy Science Association recognized the contributions of INAF’s director, Yves Pouliot, when it presented him with the 2010 International Dairy Foods Association Research Award in dairy foods processing.

Dr. Pouliot received his undergraduate and doctorate degrees in food science and technology from Laval University. He cofounded Advitech, a Quebec firm specializing in the development of bioactives from milk. After Advitech became a publicly traded company, Pouliot rejoined the Laval faculty and applied his expertise in membrane separation, first as scientific director and then director of INAF, which includes a network of 10 university and other research institutions. His work in the development of bioactives from milk has resulted in collaborations with major protein-based ingredients manufacturers, such as Davisco, Glanbia and Fonterra. Among Pouliot’s seven patents is a process for the enzymatic treatment of whey proteins to produce antihypertensive peptides.

Yves Pouliot, director, Institut des Nutraceutiques et des Aliments Fonctionnels, Université Laval, Quebec. Source: Institute of Nutraceuticals and Functional Foods (INAF).

FE: How prominent was membrane technology when you began your research activities in the 1980s?

Pouliot: Adding value to whey was the focus then. The ingredient business was booming. In the prior decade, we saw more reliable membranes being commercialized, with new materials of construction for improved chemical resistance and sanitary designs. At the time, ultrafilitration (UF) technology provided an industrial tool to process whey and add value to its protein components because of UF’s flux (separation efficiency), selectivity and ability to process large quantities. Once we discovered that UF could be used to eliminate lactose and concentrate protein, a chain reaction occurred: Each time we learned one thing, three or five other avenues of research emerged.


FE: In what areas has membrane separation had the greatest impact?

Pouliot: In dairy processing, there are three main areas: as an alternative to centrifugation, evaporation and other processes; as a way to resolve separation issues such as defatting of whey and fat globule fractionation; and as a tool for new products, such as UF cheeses and whey-based beverages. It’s estimated that more than 75 percent of total area of UF and reverse-osmosis membranes installed worldwide are used in whey processing. Milk processing alone accounts for 25 percent of the installed base of UF membranes.


FE: Many of your discoveries have been applied to life sciences, but food applications seem to lag. Why is that?

Pouliot: We have developed some processes that are ready to jump to commercial dairy use, but the economies aren’t there yet. The food industry needs affordable technology, which is why processes like chromatography have not been applied. For example, we have used chromatography and electrofiltration to isolate high-value lactoferrin. It commands a price of about $500 a pound, but you need to process 13,000 liters of milk (about 3,430 gallons) to harvest a pound of lactoferrin, and it can’t be done cost-effectively by a dairy.


FE: Significant advances in membrane technology occurred in the 1980s and 1990s. Has innovation continued?

Pouliot: Not so much. Because of mergers and consolidation, there are really only three companies left in membrane technology. In the absence of new technical tools, we have focused on ways to improve efficiencies and maintain flux.

Membrane technologies have not been fully exploited in the dairy industry for the development of bioactives and other milk-based ingredients. Unless you have a very revolutionary new product, it’s difficult for mainstream processors to justify the cost. Even when the product is revolutionary, companies often have to develop the market for it, and that takes time and money.


FE: Fluid milk achieves a richer mouthfeel after ultrafiltration. Why is that?

Pouliot: Very few researchers have studied the organoleptic effects of UF because of the complexity of the milk itself. Identification of which components are at play in affecting mouthfeel is a big question.

Some of my current work involves fractionation of buttermilk and whey buttermilk. Buttermilk is sometimes added to chocolate milk to improve the flavor, but that’s not a very high-value use. The use of UF to preconcentrate milk for cheese production has increased the availability of whey buttermilk. It contains a milk fat globule membrane that is rich in proteins and phosphilipids and could be valuable in both functional and nutraceutical applications. Fractions rich in these components could be important in improving both food systems and human health.


FE: Two of your US patents relate to the use of whey proteins for treatment of hypertension. What prompted the work?

Pouliot: Hypertension is estimated to be a factor in almost three in 10 adult deaths in industrialized countries. An ingredient company approached us to develop effective processes and dosages of hydrolysates from whey protein isolates to reduce heart rates and blood pressure associated with hypertension. Because public funding supports INAF’s work, our mission is to promote better living by expanding knowledge of human nutrition and health. Accomplishing that mission becomes more attractive when dairy ingredients are involved, since 70 percent of Canada’s milk is produced in Quebec and Ontario provinces. So when an industrial partner asks us to help address ailments like psoriasis that pose significant health risks, we are able to help. One patent involves the combination of transforming growth factor with dairy-derived proteins. The first step was to conduct a couple of pilot trials to establish the proper dosage factor so a pill that delivered an effective dosage could be made.

Buttermilk has some very interesting minor components, including some that seem to lower cholesterol. We’re beginning clinical trials this year with high-cholesterol patients to determine effectiveness and proper dosing.


FE: Is there much coordination with similar research conducted in the United States?

Pouliot: Individuals certainly collaborate. Some of my research on buttermilk has been in conjunction with researchers at California Polytechnic in San Luis Obispo. But institutionally, cross-border collaboration is difficult. The individual researcher is focused on his own work. To collaborate, you have to have open minds. It’s not natural or easy to collaborate, but it can be very effective.


FE: You have written about the shelf-life extensions made possible by the uniform transmembrane pressure concept from Tetra-Laval and the introduction of industrial-scale microfiltration. Are equipment advances ever a focus of INAF collaborations?

Pouliot: There is collaboration, but commercial secrets are a problem. Every time we begin a project, we get stuck on confidentiality issues. Most of the cooperation involves donations of fillers and other equipment to our pilot plant.

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