A team of engineers at Université Laval has developed a new system for efficiently extracting high-value bioactive molecules — potential nutraceuticals or pharmaceuticals — from plant and animal proteins.

In our gut, enzymes break up plant and animal proteins into hundreds of smaller peptides. Some of these reportedly have health benefits such as antioxidant or anti-diabetic properties; if purified and concentrated they could provide a new revenue stream for food producers. Currently, separation is usually done by size: for example, ultrafiltration uses high pressure to force the mixture through filter membranes with pore sizes ranging from 0.1 to 0.001 micrometres. The problem is fouling: peptides that don’t get through the membrane build up on its surface, reducing both its efficiency and selectivity.

A team led by Laurent Bazinet, a food engineer at Laval’s Institute of Nutrition and Functional Foods, has developed an alternative approach that combines filtration with electrodialysis, which is normally used to remove charged ions from water in desalination systems. Rather than using pressure to force particles through, the system uses an electric current to move small peptides — which in normal pH can develop positive and negative charges — through a stacked series of filtration membranes. Separating the peptides by charge as well as size improves selectivity. “We can now separate the anionic and the cationic peptides, since they will not migrate in the same way,” says Bazinet. “And since we have no pressure, we have no fouling.”

In their latest paper, published in Food Chemistry, Bazinet and his colleagues describe how the new system allowed them to simultaneously digest a large protein — β-lactoglobulin, the main component of whey protein — and extract both cationic and anionic peptides from it, including some with activity against high cholesterol and blood pressure. The team recently patented the process and is working with the Centre de Développement Bioalimentaire du Québec to install a pilot-scale device. Bazinet hopes to have it finished by 2014.