SAN FRANCISCO --- As biodiesel use moves into the mainstream, and diesel prices approach $5 a gallon, fast-food restaurants are becoming a more common target of thieves looking to steal fryer grease.

According to the New York Times, a Burger King in northern California recently discovered a thief who had pulled his truck to the back of the restaurant and dunked a tube into a smelly storage bin to vacuum out about 300 gallons of grease. Police apprehended him and found 2,500 gallons of used fryer grease in his truck.

Nick Damianidis, owner of Olympic Pizza and Pasta Restaurant in Arlington, Wash., said grease thieves have struck his business seven or eight times since last summer. He is now considering installing a security camera to keep watch over his 50-gallon grease barrel.

"Fryer grease has become gold," Damianidis said. "And just over a year ago, I had to pay someone to take it away."

Processed fryer oil, dubbed "yellow grease," is now traded on the booming commodities market. In recent months, its value has jumped to new highs. Last week, its price was nearly $2.50 a gallon.