In a statement emailed to CBC News, Heinz Canada spoke out against the proposed changes that are part of the Conservative omnibus bill.
The company said the changes took food processors by surprise.
"The regulatory changes on page 219 in the Federal Government Budget 2012 came as a surprise to many stakeholders, including municipal, provincial and federal representatives, as well as consumers, producers and processors," wrote Andrea Acic. "Of particular concern is the Canadian Food Inspection Agency’s intention to deregulate container sizes for many packaged foods sold in Canada. This change does not help consumers and has implications for producers, processors and communities.
"We encourage people to educate themselves on this issue and understand the risks and tradeoffs by visiting KeepFoodJobsInCanada.ca. Then contact their MP and the Honourable Agriculture Minister Gerry Ritz to voice their opinion."
That's precisely what southern Ontario mayors did Monday. Mayors and industry officials had a face-to-face session with Essex Conservative MP Jeff Watson.
The mayors of Tecumseh, Leamington and Kingsville fear that if the federal government repeals the law that regulates the sizes of packaged foods sold in Canada it will cost the region jobs.
Heinz, Bonduelle and Sunbrite all have operations in southern Ontario.
The change could put businesses that process food in Canada at a competitive disadvantage unless they adopt American sizes and formats, food processors claim.
Kingsville Mayor Nelson Santos said they might simply decide to move operations to the U.S., instead of investing millions of dollars in new production lines.
Tecumseh Mayor Gary McNamara said Canadian food processors will be forced to make tough decisions. They make simply move to the U.S., he said.
"These companies, many of them are multi-nationals, and are they going to invest in changing their canning lines in Canada? I don't think so," he said.
Watson said the meeting was an eye-opener and the he is now more fully aware of the situation.
He said he'll do his best to make sure Canadian operations are not affected and that Canada's food processors are not inconvenienced.
Last week, Meagan Murdoch, a spokesperson for Minister of Agriculture Gerry Ritz, said food processors who want to retool could apply for federal funds, "if they want to change their system to become more innovative and competitive."
They could do so through the AgriProcessing Initiative (API), part of the Agricultural Flexibility Fund announced in Budget 2009. The initiative is designed to enhance the competitiveness of the agri-processing sector in Canada.
Canadian food processors are not legally required to change the size of their packaging.