Soaring food prices, triggered by rising energy costs and decreased wheat supplies, have public school officials here bracing for the highest price hikes for school lunches in years.

"I honestly can't say what percent," said Martha Jo Fritz, food service director for local schools. "But we know they're going up."

Fritz heads up a regional collaborative of school districts that buys food and supplies for school lunches in bulk to keep down the cost. She said vendors have warned her that prices are going way up because of higher costs to produce and distribute staples such as milk, bread, paper and plastic.

"Delivery costs are one of the main costs in the food-supply chain," said Tom Powers, another local food service director. "Everything that travels to my food dock has traveled around the country, and fuel is very, very expensive."

Flour prices have climbed threefold - from $15 to $50 per unit - in less than a year because of diminished wheat supplies in the United States, said Rob-Roy Quinzani, owner of a 90-year-old family bakery. He sells bread to several schools throughout the Boston area.

"Schools haven't seen this coming," he said. "Never in our lifetime or in my father's lifetime have we seen anything like this."

One of the reasons, he said, is that midwestern farmers are growing more corn than wheat because of federal subsidies for corn to feed the ethanol fuel industry. At the same time, he added, the demand for American wheat has increased in China, India and other developing countries.

"They're running out of the stuff (wheat)," said Quinzani.