Heinz-Kraft merger: What's next for the industry?

Campbell Soup (CPB), Kellogg (K), General Mills (GIS) , and Mondelez International (MDLZ) are among the food companies seen by some Wall Street analysts as potential acquisition targets in light of the $40 billion merger of H.J. Heinz Co. and Kraft Foods (KRFT).

Packaged food companies have underperformed the S&P 500 Index over the past year amid investors' concerns that the companies have failed to address growing consumer demands for food they consider to be natural and healthy. Soup and cereal, which have long been a staple of the American diet, are a case in point: Data shows that people are eating less of both products.

During the latest quarter, when parts of the U.S. experienced bitterly cold weather, Campbell Soup said sales of its flagship product slumped 6 percent. Condensed soup sales plunged 11 percent. Kellogg, whose brands include Froot Loops, reported a 7.7 percent fourth quarter decline in the U.S. in the morning foods business while Cheerios parent General Mills reported that cereal sales were flat.

"Any of these companies could potentially be targets," said Brian Yarbrough, an analyst with Edward Jones, in an interview, adding that he expects 3G and Warren Buffett to buy more food companies in the next few years. "They aren't combining Heinz and Kraft and calling it a day."

3G Capital, a Brazil-based hedge fund that joined forces with billionaire Warren Buffett to acquire Kraft, hasn't been shy about writing big checks. It acquired Burger King for $3.25 billion in 2010 and subsequently merged the fast-food chain with Canadian donut shop operator Tim Hortons. The combined company trades under the name Restaurant Brands International (QSR).

3G's financing partner in the Burger King deal was Buffett. They joined forces again in 2013 for a $23 billion deal to acquire H.J. Heinz. The firm, which is headed by Brazilian billionaire Paulo Lemann, has also made a splash in the beer business. Lemann merged Brazil's largest breweries and sold them to Belgium-based Inbev, which in turn acquired U.S.-based Anheuser-Busch in 2008 to create Anheuser-Busch InBev (BUD).

The current Kraft Foods company was created in 2012 after the faster-growing Mondelez snack business, which includes Oreo cookies, split off. Since then, Kraft has struggled with lackluster sales.

Some investors say they are losing patience with the sector. "You could see some activist investors get involved," said Timothy Ghriskey, who helps manage $1.5 billion for Solaris Capital Management, and has stayed clear of packaged food companies. "It's certainly a deal that makes you sit up and take notice."

So are some food companies in a selling mood?

A Campbell spokesman said it was against company policy to comment on rumors and speculation, and officials from Kellogg, General Mills and Mondelez also declined to comment.

News of the Heinz merger pushed Kraft shares up more than 35 percent to $83.17. Combining Heinz and Kraft will create the world's fifth largest food company, home to such well-known brands as Ore-Idea potatoes, Jell-O, Maxwell House coffee and Oscar Mayer processed meats.

Buffett has said he was on the lookout for an big deal to add to his Berkshire Hathaway (BRK.A) conglomerate. He added that there is still plenty of room for Heinz to expand internationally, joking to CNBC that you can add ketchup to anything.

That's easier said than done.