The U.S. Food and Drug Administration has been sampling frozen strawberries, frozen raspberries and frozen blackberries for the presence of norovirus and hepatitis A since last November.
The agency noted four foodborne illness outbreaks between 1997 and 2016 were linked to frozen berries — three caused by hepatitis A and one by norovirus. The three hepatitis A outbreaks sickened 405 people and caused 53 hospitalizations, while the norovirus outbreak sickened 136, FDA said. Other illness outbreaks linked to frozen berries have occurred in Europe and elsewhere, the agency added.
The testing will last about 18 months, FDA said, and involves domestic samples in retail packaging from processors, distribution centers, warehouses, and retail locations. Samples of imported frozen berries will be gathered from ports of entry, importer warehouses and other storage facilities where foreign goods are cleared for entry into the U.S. The agency plans to test 2,000 samples and post quarterly results online.
Because frozen berries are usually consumed raw, it's possible for them to transmit foodborne illnesses since there's no kill step such as cooking to reduce or destroy pathogens. As FDA noted, freezing preserves berries, but generally does not kill pathogens, which can survive at low temperatures.
How the fresh berries are treated after being picked is also crucial.
"Strawberries, raspberries, and blackberries are delicate and may become contaminated with bacteria or viruses if handled by an infected worker who does not use appropriate hand hygiene or if exposed to contaminated agricultural water or a contaminated surface, like a harvesting tote," the agency said.
FDA said it will not notify firms before collecting samples of frozen berries, which might behoove producers to ramp up testing protocols in the fields or processing plants beforehand. If hepatitis A or norovirus is found in product samples, the agency said it will inform the company and work with it to "take appropriate action to protect the public health." This could include an import alert, a recall or a public warning.
A producer of tainted frozen berries could also announce its own recall, post the information on its website, work with retailers to inform shoppers, and text or call consumers who bought the item and inform them of the danger. However, knowing FDA could suddenly show up to conduct sampling may be enough of an incentive to make sure frozen products are as close to pathogen-free as possible.
FDA has been sampling different food items since the Food Safety Modernization Act passed in 2011. It began using a more systematic approach to sampling in 2014 by testing sprouts, avocados and raw milk cheese for salmonella, listeria and E. coli. After that, it checked on cucumbers and hot peppers for salmonella and E. coli. Fresh herbs were next, with FDA sampling basil, parsley and cilantro for salmonella, E. coli and cyclospora. In fiscal 2018, the agency looked into processed avocado and guacamole for salmonella and listeria monocytogenes.
This approach could prove useful and protective if the sampling method reveals patterns in pathogen transmission that have previously been overlooked, as The New Food Economy pointed out. Berries packed in the summer might be more likely to have norovirus contamination from something in the field, for example, while samples showing hepatitis A may come from the same area and indicate a problem with contaminated water.
As the FSMA Produce Safety Rule fully kicks in, and with routine inspections of domestic and international produce farms underway this spring, the collective impact could be fewer outbreaks traced to frozen berries and other fresh products. On-farm inspections and other regulatory and operational changes may finally start to get a handle on U.S. and foreign produce contamination. These practices may give consumers more confidence when it comes to buying and consuming fresh produce — as well as frozen.