Dairy, biofuel byproducts offer new route to films.

Economic pressures on dairy farmers and processors require them to more effectively utilize their products and byproducts. USDA-RS research is focusing on ways to develop new food and non-food uses for whey and casein, as well as nonfat dry milk (NFDM), through basic research and process development engineering.

Specifically, new processing techniques for the production of edible films from milk proteins are under investigation to expand their utilization into new food and nonfood products. Scientists also are examining high pressure and supercritical carbon dioxide (C[O.sub.2]) as media for creating modified casein and whey proteins to increase the functionality of the proteins for food uses.

The average American consumes more than 30 pounds of cheese every year. Every pound produced creates an estimated 9 pounds of whey, the liquid byproduct that remains after the curds, or solids, coagulate. This whey is used in a range of products such as candy, pasta, baked goods, animal feed and drugs.

Now, a technique developed by USDA-ARS scientists uses byproducts--not only from dairy processing, but also from biofuel production--to create biodegradable films. Investigators found that by combining the milk protein casein with water and glycerol, a byproduct of biofuel production, they were able to produce a water-resistant film that can be used as an edible coating on foods.

The scientists used C[O.sub.2] as an environmentally friendly solvent to isolate dairy proteins from milk. They used C[O.sub.2] instead of harsh chemicals or acids that can be difficult to dispose of. C[O.sub2] is another byproduct of the glucose fermentation that is used to make ethanol. Using C[O.sub.2] makes the edible film more water-resistant and biodegradable. The resulting coatings are glossy, transparent and completely edible. By using renewable resources instead of petrochemicals, the scientists were able to create more biodegradable products and reduce waste.

The USDA group had been working to improve the appearance and protective properties of casein films. At one point in their production process, the C[O.sub.2] dissolves into the milk, decreasing its pH level and causing casein to form particles of a substance known as C[O.sub.2]-casein. The researchers found that decreasing the size of the C[O.sub.2]-casein particles improved the film's ability to block moisture and increased its glossiness. They also found that coating a low-density polyethylene film with the C[O.sub.2]-casein material increased the film's ability to block oxygen permeation.

Further information. Peggy Tomasula, USDA-ARS Dairy Processing and Products Research Unit, Eastern Regional Research Center, 600 E. Mermaid Lane., Wyndmoor, PA 19038; phone: 215-233-6703; fax:215-233-6795; email: peggy.tomasula@ars.usda.gov.