Separation Technology

Proteins Found Within Whey May Offer Expanded Marketing Potential

New milk protein extraction and purification techniques could prove beneficial for the cosmetics, food and pharmaceutical industries. Investigators in UC Davis' Department of Food Science and Technology are exploring novel ways to separate the various soluble proteins in milk (whey proteins) from each other.

Currently, excess whey produced during cheese-making can be processed to recover a mixture of whey proteins, and these can be sold for use as a food ingredient. However, individual proteins in the whey protein mixture may have even greater value if they can be separated from the rest. For example, alpha-lactalbumin could potentially be added during infant formula manufacture to make the product more closely match mother's milk. Beta-lactoglobulin has better functional properties (gel, foam, edible film and emulsion formation) on its own than it does in a mixture, and immunoglobulins and lactoferrins have pharmaceutical applications. Thus, if cost-effective tools can be developed to separate these proteins from each other in the whey protein mixture, the proteins could be sold for much more than the original whey mixture. A similar principle can be applied to milk and milk products.

Stephanie Dungan, an associate professor in the UC Davis Department of Food Science and Technology, is a member of the research team investigating extraction technologies and potential applications of whey protein. Dungan's research group is evaluating an unusual method for the extraction and purification of milk proteins that utilizes an organic solution known as a reversed micellar phase. This solution contains tiny water droplets, stabilized within the organic solvent by a surfactant.

"Many protein molecules will readily solubilize within these small water droplets, and for this reason can be extracted into these organic solvents from an aqueous mixture," explained Dungan. "Micellar extraction methods have been shown to be an effective approach for concentrating and purifying proteins, because they can readily be carried on a large industrial scale and because they often preserve the properties of the protein molecule during the extraction process."

Dungan's current project explores the utility of this separation method for obtaining whey protein mixtures with improved commercial properties. Her group measured the amount of various whey proteins that can be taken up by the reversed micellar solutions first from pure protein solutions, then from protein mixtures. The final step will be extraction from whey itself. Dungan and her colleagues have established that alpha-lactabumin and beta-lactoglobulin can, indeed, be incorporated within reversed micelles and thus can be extracted from pure protein solutions and mixtures. The extraction of immunoglobulin G, an important pharmaceutical protein, has also been studied.

"Much of the research has focused on determining how the conditions of the system can be tailored in order to produce protein blends of desired composition. Our future work will focus on extracting proteins directly from whey and exploring recovery methods for the protein," said Dungan.

Reversed micellar separations offer the potential for continuous liquid/liquid extraction coupled with a non-destructive protein environment. With the need for cost-effective, large-scale techniques for concentrating and purifying useful protein products from milk, reversed micellar systems could be an important tool for obtaining these valuable food ingredients.

Taken from Dairy Dispatch (Spring 1998) produced by the California Dairy Research Foundation.