Company officials visited the site last week, and say they believe someone bought their product, Heinz Ketchup, in bulk, and attempted to transfer it to bottles labeled "Simply Heinz," a premium variety of the ketchup made with sugar instead of high fructose corn sweetener.
The warehouse had hundreds of crates holding thousands of fraudulently labeled bottles of ketchup, The (Newark) Star-Ledger reported Thursday.
"The site of this operation was abandoned and had produced only a small quantity of bottles, much of which was still on site," company official Michael Mullen said in an email.
Acids in the tomatoes and vinegar, combined with fermenting sugars, leading to exploding bottles and the splattering of ketchup, followed by flies and other insects, which caught the attention of other warehouse tenants, said Richard Rosell, Dover public safety director.
Mullen said Heinz is working with the U.S. Food and Drug Administration's Office of Criminal Investigation, adding, "Heinz will not tolerate illegal repackaging of our products."
The warehouse space is leased to a firm named Wholesome Foods LLC, the newspaper said.