Dean Foods' (NYSE:DF) stock price is all over the place lately. It has moved almost 34% from its three-month low, and yesterday, the stock rose more than 8% in anticipation of today's second-quarter earnings report. Today, the stock was back down by as much as 10% in early trading, as management tempered future growth estimates with commodity price increases.

If you look at the numbers, though, you see that the news isn't that bad for Dean Foods, especially compared with last year's Q2 results. Revenue was up 9.1% for this quarter with a cost of goods sold increase of only 9.6% -- not bad considering the rampant, across-the-board commodity inflation plaguing food producers.

Core milk volume increased by only 1.1%, with the additional revenue gain attributed to the pass-through of commodity costs. WhiteWave-Morningstar -- the organic and soy milk segment -- registered a net sales increase of 10%, with Horizon Organic milk alone delivering a revenue bump of 30%. Compared with last year's dairy revenue gain of 16% and raw-milk expense increase of 48%, it's no wonder that Dean is trumpeting its 10% quarterly adjusted growth in earnings per share.

Hershey (NYSE:HSY), Kellogg (NYSE:K), and General Mills (NYSE:GIS) are among many foodies that continue to increase prices in light of rising commodity prices. So far, these companies have been able to maintain volume in spite of higher prices. Inflation has become front-page news and has perhaps given these food producers and others, including Heinz (NYSE:HNZ) and Kraft (NYSE:KFT), additional pricing power for the time being.

Like last year, Dean is advising investors that inflation and price competition will continue to affect results. The company has admitted that although its organic milk sales have risen considerably, price increases in raw milk are eating into profits. A key factor in Dean's continued growth is whether organic milk -- or even Dean's standard milk products -- will become a luxury in a struggling economy.

With so much uncertainty, it looks as though Dean's stock price will continue to fluctuate in the same way that the market has been lately.

For related Foolishness:

Kraft and Heinz are Income Investor selections. Hungry for more investing advice? Give The Motley Fool's newsletter services a shot with a 30-day free trial.

Fool contributor Colleen Paulson does not hold positions in any of the stocks mentioned above and will keep drinking milk even if its costs more per gallon than gas. The Fool's disclosure policy isn't a commodity.