Researchers at the US Department of Agriculture (USDA) say they have found a way to create uses for the billion of kilos of whey produced every year by processors. The development could provide a way for them to make a profit from unused whey and to benefit from another source of biodegradable packaging. USDA food technologist Charles Onwulata said he has used a process called reactive extrusion to supplement polyethylene -- a common nonbiodegradable plastic -- with whey proteins. He uses reactive extrusion to force plastic material through a heating chamber, where it melts and combines with a chemical agent that strengthens it before it's molded into a new shape. Onwulata's research showed that by combining dairy proteins with starch during the process, it's possible to create a biodegradable plastic product that can be mixed with polyethylene. Working with another researcher Onwulata has also created a bioplastic blend. They combined whey protein isolate, cornstarch, glycerol, cellulose fiber, acetic acid and the milk protein casein and molded the material into cups. The dairy-based bioplastics proved to be more pliable than other bioplastics, which made them easier to mold, they claimed. The blends can only replace about 20 per cent of the polyethylene in a product, so resulting materials would be only partially biodegradable, they noted. However, Onwulata and his colleagues are currently applying the process to polylactide (PLA), a biodegradable polymer. The research could someday result in completely biodegradable bioplastics, they said.