NEW YORK - The forces behind the rise in food prices - China's economic boom, a growing biofuels industry, and a weak US dollar - are global and not letting up anytime soon. Grocery receipts are bulging because the raw ingredients, packaging, and fuel that go into the price of foodstuffs cost more than they have in decades.
It's the worst bout of food inflation since 1990, but not yet worrisome to the economy, said John Lonski, chief economist of Moody's Investor Service. While high food prices can cut into consumers' discretionary spending, the 4 percent rate of food inflation is still far below the crippling double-digit levels of the 1970s.
Still, consumers anxious for relief in the checkout line may have to wait.
Andrea Williams, 32, can track the rise in prices of the food she buys for herself, her husband, and their three children by looking back at the receipts she says she meticulously saves.
"In 2004, I bought a gallon of milk, it was a $1.63," Williams said before heading into a Wal-Mart in Savoy, Ill.
A gallon of milk cost nearly $3 a gallon last month in her area.
A couple of years ago, Williams would spend about $250 a month on one big grocery trip. Now she says she spends $250 every two weeks.
It is possible to trace the jump in food costs to the commodities markets, where the price of agriculture products and energy have reached multidecade highs this year. Crude oil, which helps dictate the price of gasoline and plastic packaging, hit a record in September. Wheat prices also climbed to a record.
The run-up in commodity prices has as much to do with short-term supply and demand in each market as with long-term shifts in who produces and consumes those products.
China is the juggernaut. Rapid growth there - and in Brazil, Russia, India, and other developing nations - has led to massive demand for raw materials, including energy to run factories and cars, metals to build infrastructure, and beans and grains to feed livestock and people. China will import almost 50 percent of the world's oilseeds within a decade, becoming the world's largest importer, according to estimates from the Organization for Economic Cooperation and Development.
Oils made from oilseeds such as soybeans are used widely in packaged foods, while corn is used to make high fructose corn syrup, a sweetener found in everything from soda to bread.
China's oilseed demand reflects another trend: The world is using more of its food supply to make fuel. Corn in the United States and China is being converted to ethanol, a gasoline additive. Europe is using more wheat for ethanol and rapeseed for biodiesel, a cleaner burning fuel that is mixed with regular diesel. Brazil has bulked up its production of sugarcane to make ethanol.
Demand from the burgeoning ethanol industry in the United States helped drive corn prices to a peak this year, setting in motion a domino effect of price increases through the food chain as livestock raisers, food makers, and retailers tried to recover costs.