For more than a year, food manufacturers have been shaving package sizes and raising prices, declaring that they had little choice because of unprecedented increases in the cost of raw ingredients like corn, soybeans and wheat.

    Now, with the price of grains and other commodities plunging, it may seem logical that grocery prices will follow. But while prices for some items like milk and fresh produce are dropping, those of most packaged items and meat are holding firm or even increasing. Experts warn that consumers should not expect lower prices anytime soon on most items at the grocery store or in restaurants.

    Government and industry economists project that the overall cost of food will continue to climb in 2009, led by increases for meat and poultry. A big reason, they say, is that food companies still have not caught up with the prolonged run-up in commodity prices, which remain above historical averages despite coming down from their highs early this year.

    The Agriculture Department is forecasting that food prices will increase 3.5 to 4.5 percent in 2009, compared with an estimated 5 to 6 percent increase by the end of this year.

    Some economists project even steeper increases next year. For instance, Bill Lapp, principal at Advanced Economic Solutions in Omaha, said he expected food prices to jump 7 to 9 percent next year.

    “For the last 21 months, food manufacturers, restaurants and livestock producers have been absorbing significant costs that in my view are likely to be passed on to consumers in 2009 and beyond,” said Mr. Lapp, a former chief economist at ConAgra Foods.

    While predicting future food prices is an inexact science, data released by the Labor Department last week suggested the forecasters might be right.

    Overall consumer prices recorded the biggest drop in the history of the Consumer Price Index, but food prices continued to inch upward, albeit at a slower pace than in previous months. The C.P.I. showed that grocery prices rose 0.1 percent in October.

    Some of the more visible items on grocery shelves, including produce and dairy products, dropped sharply in recent weeks, but not enough to offset the general trend of rising prices. Restaurant prices rose 0.5 percent in October.

    Commodity prices began climbing rapidly in the fall of 2007, and food companies were hit hard by the increases. They tried to slow eroding profit margins by cutting operating costs, making packages smaller and raising prices.

    Some companies, like Kellogg and Heinz, have managed to offset the higher ingredient costs and post robust profits by using shrewd commodity hedges and by raising prices without losing many customers. They also benefited from a trend of consumers eating out less and buying more groceries.

    But other food companies have struggled. Hershey, for instance, locked in high cocoa prices this year only to see prices drop this fall, analysts say. And meat and poultry companies have been hit by higher feed costs and a limited ability to charge higher prices, at least in the short term.

    Now, even though costs for ingredients like corn and wheat have dropped, meat and poultry providers say they still have not raised prices enough to cover their increased costs. And packaged food manufacturers are unlikely to lower prices because commodity costs remain relatively high and they are still trying to rebuild eroded margins.

    Michael Mitchell, a spokesman for Kraft Foods, said that the company’s food ingredient costs this year were running $2 billion higher than in 2007, a 13 percent increase, but that the company had raised its overall prices by only 7 percent.

    William P. Roenigk, senior vice president and chief economist for the National Chicken Council, said his industry had been losing money for more than a year. Chicken producers are now trying to recover those costs by reducing production, which will eventually alter the balance between supply and demand. “The time is coming when we’re going to see a very significant increase in the retail price of chicken,” he said.

    The restaurant industry, which has been battered by a sharp drop in customers, also says it has not been able to raise prices enough to keep pace with the cost of ingredients.

    People in the restaurant business said they did not like raising prices during an economic downturn. “If anything in this environment, one would be looking at the ability to offer much greater emphasis on value pricing in restaurant menus,” said Hudson Riehle, chief economist of the National Restaurant Association. “In contrast, exactly the opposite is happening. Our operators are being forced to raise menu prices at the highest rate since 1990.”

    Predictions about food prices are subject to change because commodity prices are unpredictable. Ephraim Leibtag, an economist for the Agriculture Department, said food inflation would slow by the middle of next year if commodity prices remained low. “Right now the forecast is about 4 percent, but that would be lowered if we do not see any surge in commodity costs over the next few months,” he said.

    A reason that overall food prices are expected to continue increasing is the lag between price increases for basic commodities and for finished food products in the grocery store, particularly for meat and processed foods. Consider the price of corn, an ingredient in things like cereal and breaded shrimp. It was not too long ago that corn hovered around $2 or $3 a bushel.

    But corn prices began climbing last fall and peaked around $8 a bushel in June. They have since dropped to about $3.50 a bushel, still above the historical norm. Some food manufacturers locked in prices for corn and other commodities in the spring and summer, fearing that prices could go even higher. But prices fell instead, and they are now stuck with the higher prices until their contracts expire.

    When costs go up for livestock producers, they are often unable to immediately raise prices because those prices are set on the open market, which is dictated by supply and demand. Instead, they begin reducing the size of their herds or flocks, which eventually leads to less meat on the market and higher prices. But reducing livestock production can take months to years, and in the interim it can actually suppress prices as breeding animals are slaughtered to reduce production.

    The prospect of more food inflation is inflaming a debate over its causes. Many food manufacturers and economists maintain that one culprit is government policies promoting the use of ethanol fuel made from corn.

    About a third of the corn crop is used for ethanol, putting ethanol producers in competition with livestock farmers and food manufacturers. The result, they contend, is that prices for corn are now higher and more volatile.

    “The connection of oil prices to agricultural commodities is new as of 2007, and it’s a major game changer for those in the food production business,” said Thomas E. Elam, president of FarmEcon, a consulting firm.

    But ethanol advocates counter that the food industry’s arguments have been proved false, saying that corn prices have declined as ethanol production is increasing. Matt Hartwig, spokesman for the Renewable Fuels Association, an ethanol industry group, said food companies were “very quick to tell the American public that they had to raise food prices because corn was so expensive, and that the reason corn was so expensive was corn-based ethanol.”

    Mr. Hartwig added: “Now, clearly, we know that relationship doesn’t exist. If ethanol isn’t the reason, what is the real reason for food prices going up?”

    一年多以來，食品制造商宣稱，由于玉米、大豆和小麥等原料價格空前上漲，他們幾乎沒有選擇，唯有削減包裝尺寸，抬高價格。

    現在，隨著谷物和其他消費品價格的飛躍上升，食品價格跟著上漲似乎大有可能。盡管有些東西如牛奶和水產品的價格正在下降，但大部分的包裝物和肉類的價格依然堅挺甚至還在上升。有專家警告說，消費者任何時候都不要奢望在雜貨店或飯店里的消費會很快地有所下降。

    政府和產業經濟學家預言，食品總成本在2009年會繼續爬升，肉和禽類更為領先。他們說，一個最大的原因就是，盡管曾從年初的高價位跌落，食品企業仍然沒有追趕上初級商品價格長時間的升高，還保留在歷史平均數之上。

    農業部門預測，與估計的截至今年年底的5-6%的價格上漲相比較，2009年食品價格將上漲3.5-4.5%。

    還有一些經濟學家預測，明年上漲的幅度甚至更大。比如，Bill Lapp，奧馬哈高級經濟研究所的負責人就說，他預計明年食品價格會上升7-9%。

    還有一些經濟學家預測，明年上漲的幅度甚至更大。比如，Bill Lapp，奧馬哈高級經濟研究所的負責人就說，他預計明年食品價格會上升7-9%。

    盡管預報未來食品價格是一門不精確的學問，但勞工部上周公布的資料卻暗示預測可能是準確的。

    所有零售價格都記載了消費物價指數歷史上的最大下跌幅度，但食品價格卻繼續步步見漲，雖然在先前的幾個月中速度有所減緩。

    雜貨店貨架上更多可見的商品，包括農產品和乳制品，在最近幾周價格跌得很厲害，但不足以抵消價格升高的總體趨勢。10月份，飯店的價格就提高了0.5%。

    農產品價格在2007年秋季開始升得很快，食品企業受到此次物價上漲的嚴重打擊。他們設法通過裁減運營成本、改小包裝和提高價格來慢慢蠶食利潤空間。

    有些企業，象家樂氏和亨氏，通過運用精明的農產品限制和提高價格來設法抵消越來越高的配料成本和穩定強勁的利潤，同時又不致喪失大量的消費者。他們也受益于這一趨勢——消費者外出就餐日益減少而購買更多的食品。

    可是另外的食品企業卻在掙扎。分析家說，例如好時公司，巧克力價格居高不下，只有在這個秋季才看到有所下調。肉類和禽類企業因飼料成本越來越高、至少在短期內調高價格能力有限而倍受打擊。

    現在，即使諸如玉米和小麥之類的農作物成本下跌，肉類和禽類供應商也會說他們依然沒有把價格提高至足以將他們增加了的成本包含在內。包裝食品制造商未必會降低價格，因為農產品成本依然比較高，他們依舊想方設法重建越來越小的利潤空間。

    卡夫食品發言人Michael Mitchell稱，該公司食品配料成本今年比2007年多花了20億美元，增加了13%，但公司全部商品價格只提高了7%。

    William P. Roenigk，全國雞肉理事會的高級副會長和首席經濟學家反映，他的工廠虧損已一年多了。雞肉生產商現在正試圖通過減產來彌補成本費用，這將最終改變供需平衡。“我們將看到雞肉零售價猛升的時刻正在到來。”他說。

    由于顧客銳減而被弄垮的餐飲業也說，他們不可能將價格充分提高以跟上材料成本。

    餐飲行業人士說他們也不愿意在經濟低迷時期拉高價格。“如果這種環境下能做什么的話，那一定是著眼于大力強調餐廳菜單價值定價的能力。”美國國家餐館協會首席經濟學家Hudson Riehle說。“相反，現在發生的情況卻恰恰相反。我們的經營者正被迫進行自1990年以來最大幅度的提價。”

    預言食品價格將改變是因為物價不可預知。Ephraim Leibtag，農業部門的一位經濟學家說，如果物價維持在低水平的話，食品通脹到明年年中會減緩。“現在預測為大約4%，但假如往后幾個月看不到物價飆升，那有可能會低一點。”

    預期所有食品價格繼續上漲的一個原因就是，基本商品和雜貨店里食品成品價格上漲之間的滯后，尤其是肉和加工過的食品。仔細看看玉米，麥片粥和沾滾過面包屑的小蝦之類的配料就知道了。不久前玉米價格還徘徊在2-3美元一蒲式耳呢。

    不過玉米價格去年秋天就開始攀升了，6月更是達到了峰頂值——要8美元一蒲式耳。即使價格又回落到3.5美元一蒲式耳了，可依然還是高于歷史標準。有些食品生產商在春夏兩季囤積玉米和其他商品，因為他們擔心價格會越來越高。但相反，價格下跌了，而他們現在還得付高昂的價格直至合約期滿。

    對牲畜產出商家而言，當成本上升時，他們常常不能立即提價，因為那些價格建立在公開的由供需關系支配的市場之上。他們取而代之的，是開始減小牛羊喂養的規模，那最終會導致市場肉類減少、價格上升。但減少牲畜產出也只能維持幾個月到幾年，臨時起到實際抑制價格的作用，如果屠殺喂養的動物以減少產出的話。

    更大食品通脹很可能激起一場有關其原因的大辯論。許多食品制造商和經濟學家堅持，一個原因就是政府政策提倡大量使用由谷物提煉而來的乙醇燃料。

    大約三分之一的農作物被用于制作乙醇，使得乙醇生產商同牲畜農場主以及食品制造商去競爭。他們競爭的結果，就是現在谷物的價格越來越高、越來越反復無常了。

    “油價和農業商品的關系不同以往，就象2007年，它是那些食品生產企業的主游戲操控者。”咨詢公司FarmEcon總裁FarmEcon說。

    但乙醇擁護者反擊，食品工業的爭論是錯誤的，他們說，當乙醇生產加大時谷物價格卻在跌落。Matt Hartwig，可再生燃料協會乙醇工業群體的發言人說，食品公司“很快會告訴美國民眾，他們不得不加價是因為谷物是如此昂貴，谷物如此昂貴的原因就在于基于谷物而生產的乙醇。”

    Hartwig先生補充道：“現在，我們非常清楚地知道，那種關系并不存在。如果乙醇不成其原因，那食品價格上漲真正的原因是什么？”