TreeHouse Foods has expanded its board of directors, from seven to nine members.

“TreeHouse has doubled in size since its public debut in 2005, and the board has concluded that expansion in size was appropriate in light of the increased workload of the board and complexity of the business,” chairman and CEO Sam Reed said.

The US food maker has appointed Dennis O’Brien and David Vermylen to join its board.

O’Brien has been a partner at private equity group Gryphon Investors since April 2008. Prior that, he was CEO of Penta Water Co. O’Brien also held a series of executive positions with ConAgra Foods, including president and chief operating officer for retail products, TreeHouse added.

Vermylen has served as the company’s president and chief operating officer since January 2005.