The average American consumes more than 30 pounds of cheese every year. Every pound produced creates an estimated nine pounds of whey, the liquid byproduct that remains after the curds (solids) coagulate. Where does all the whey go? It’s used in a range of products such as candy, pasta, baked goods, animal feed and even pharmaceuticals.

Since its inception, Agricultural Research Service’s (ARS’s) Dairy Processing and Products Research Unit at the Eastern Regional Research Center (ERRC) in Wyndmoor, Pennsylvania, has investigated uses for whey and other dairy byproducts. Today, thanks in part to ERRC research, cheesemakers have markets for over one billion pounds of whey every year.

New research shows that whey can also be used to create eco-friendly products. For example, using a process called “reactive extrusion,” food technologist Charles Onwulata supplements polyethylene (a common nonbiodegradable plastic) with whey proteins. Reactive extrusion involves forcing plastic material through a heating chamber where it melts and combines with a chemical agent that strengthens it before being molded into a new shape. Onwulata showed that by combining dairy proteins with starch during this process, it is possible to create a biodegradable plastic product that can be mixed with polyethylene and molded into utensils.

Working with laboratory chief Seiichiro Isobe of the Japanese National Food Research Institute, Onwulata created a bioplastic blend by combining whey protein isolate, cornstarch, glycerol, cellulose fiber, acetic acid and the milk protein casein and molded the material into cups. Onwulata observed that dairy-based bioplastics were more pliable than other bioplastics, making them easier to mold.

Bioplastic blends can replace only about 20 percent of the polyethylene in a product, so resulting materials are only partially biodegradable. But Onwulata and his colleagues are currently applying this process to polylactide (PLA), a biodegradable polymer.

“Blending dairy-based bioplastics with PLA could eventually allow producers to make completely biodegradable materials,” he says.  PD

—From Agricultural Research, May/June 2007