Eric and Ryan Jensen were charged with introducing adulterated food into interstate commerce.
The brothers pleaded not guilty at the hearing this week and were released with a trial scheduled for 2 December. They called the outbreak a “terrible accident”, according to the Associated Press news agency.
A US Food and Drug Administration (FDA) and Center for Disease Control (CDC) investigation determined that the defendants failed to adequately clean their cantaloupe.
Their actions allegedly resulted in at least six shipments of cantaloupe contaminated with Listeria monocytogenes being sent to 28 different states.
The firm filed for bankruptcy in May of last year after the incident which was officially recognised as the worst foodborne outbreak in US modern history.
CDC tracked the outbreak-associated illness and determined that people living in 28 states consumed contaminated cantaloupe, resulting in 33 deaths and 147 hospitalizations.
One woman pregnant at the time of her outbreak-related illness had a miscarriage and ten additional deaths not attributed to Listeriosis occurred among people who had been infected by eating outbreak-related cantaloupe.
According to the six-count Information filed under restriction this week and other court records, the cantaloupe bore Listeria monocytogenes and was prepared, packed and held under conditions which rendered it injurious to health.
Court documents state that the defendants set up and maintained a processing center where cantaloupes were taken from the field and transferred to a conveyor system for cleaning, cooling and packaging.
The equipment should have worked in such a way that the cantaloupe would be washed with sufficient anti-bacterial solutions so that the fruit was cleaned of bacteria in the process.
A joint investigation found that the Jensen brothers allegedly changed their cantaloupe cleaning system in May 2011.
Built to clean potatoes it was installed and included a chlorine spray to clean the fruit of bacteria but it was never used. The spray would have reduced the risk of microbial contamination of the fruit.
Both defendants face up to one year in prison if convicted and a fine of up to $250,000 for each of the six charges.