Process proteins using high-pressure gases and supercritical fluids.

Supercritical fluids are highly compressed gases that combine the properties of gases and liquids in an intriguing manner. Xenon, ethane and carbon dioxide can be used supercritically to extract product selectively.

Supercritical fluid extraction is more efficient than traditional solvent separation methods. Supercritical fluids are selective, providing high purity and product concentrations. Additionally, there are no organic solvent residues in the extract or spent biomass. Extraction is efficient at modest operating temperatures, for example, at less than 50 C, ensuring maximum product stability and quality.

Investigators want to develop new environmentally benign processes for dairy protein modification that utilize supercritical fluids as reaction media and solute carriers. They'd like to create new processes for producing enriched fractions of whey and casein proteins to utilize surplus NFDM and whey.

Specifically, new processing techniques for the production of edible films from milk proteins will be investigated to expand their use in food and nonfood products. The researchers are looking at using high pressure and supercritical carbon dioxide as media for creating modified casein and whey proteins that increase the functionality of the proteins for food uses.

A new, environmentally benign process will be designed based on one that was developed by ARS scientists for the fractionation of whey protein concentrate into two enriched fractions: alpha-lactalbumin (a-LA) and beta-lactoglobulin (B-LG). The investigators will use modeling and simulation to guide process development toward the most efficient production scheme.

In addition, the production of a fully soluble form of a-LA and a form in the so-called molten-globule state will be investigated. This will ultimately expand the range of products that can be obtained from a single process, reducing the costs associated with whey protein concentrate. Casein molecular models developed previously by the scientists will be used to guide production of enriched fractions of the individual caseins.

Further information. Peggy M. Tomasula, Dairy Processing and Products Research Unit, USDA-ARS Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038; phone: [phone]; fax: [phone]; email: [e-mail].