Peltz, who owns investment firm Trian, paid $750m for a 5.5% stake in Heinz and has demanded job cuts and factory closures, so that the savings can be used to market Heinz's products.
He has nominated himself and four other people to join Heinz's board of 12 directors.
The company's 300 million shareholders began voting on the changes at Heinz's annual general meeting yesterday, but the process could take a number of weeks.
William Johnson, chief executive of Heinz, said: “I'm optimistic they're not going to get five seats on our board. I'm optimistic they're not going to get four seats. Beyond that, we just don't have enough information.”
Heinz said in a statement: “Heinz believes, based on its preliminary estimates, that shareholders will not elect all five of Trian's nominees.”