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Microorganisms of Concern During Transport and Their Potential Sources

It is well accepted that it is the food industry’s responsibility to transport foods in a manner that presents a minimum level of risk to consumers from foodborne hazards. Therefore, the industry must identify and control potential risks from various sources, including pathogenic microorganisms. Cross-contamination (transfer of harmful bacteria to food from other foods when improperly handled) between products during shipment and from transport vehicles from prior shipments remains a significant issue.

In a 2009 US Food and Drug Administration (FDA) report, the main factors that increase the likelihood of food contamination were identified: improper refrigeration, transport of raw meat and poultry in a manner that could result in cross-contamination of fresh fruits and vegetables transported in the same vehicle, improper packing, infestation with insects, insanitary storage (e.g. roof leaks and moldy walls, animal blood and food on bed floors), low driver awareness of safe food temperatures, and inadequate training (1). Some microorganisms are of greater concern during food transport because they are part of the natural gut microflora of most food producing animals, widely found in the environment, frequently found on food con-tact surfaces, are potential sources for most foodborne illnesses, hospitalizations, and deaths in the United States (2). Table 1 lists the microorganisms of greatest concern during food transportation. 


Table 1. Microorganisms of concern during transport of foods


Commonly Associated Foods

Control Measures During Transport


Meats, eggs, fruits, vegetables, dry foods, like spices and raw tree nuts

Salmonella bacterium is hard to wash from food, even with soapy water, so important measures for preventing Salmonella foodborne illnesses include keeping raw foods separated from cooked foods, and keeping foods refrigerated at 40ºF or below


Poultry products, unpasteurized (“raw”) milk and cheeses made from unpasteurized milk, and contaminated water

Typically, each contaminated poultry carcass can carry 100 to 100,000 Campylobacter cells. Avoiding cross contamination of uncooked items from raw meat and poultry products, through good hygienic practices

E. coli

Raw beef products, raw milk, unpasteurized fruit juices, pro-duce contaminated with fecal matter

Escherichia coli is part of the normal intestinal flora in the human gut so avoid transmission through good hygienic practices; keeping raw foods separated from cooked foods, and keeping foods refrigerated at 40ºF or below


Raw milk, inadequately pasteurized milk, chocolate milk, cheeses (particularly soft cheeses), ice cream, raw vegetables, raw poultry and meats, fermented raw-meat sausages, hot dogs and deli meats, and raw and smoked fish and other seafood

L. monocytogenes can grow in refrigerated temperatures, making this organism a problem for the food industry. Potential contamination sources include food workers, incoming air, raw materials, food processing environments, and food-contact surfaces. Avoid cross contamination thorough good hygienic practices



Table 2. Outbreaks associated with food contamination during transportation





Multi-state outbreak of salmonellosis associated with ice cream mix contaminated during transport in tanker trucks that had previously hauled raw liquid eggs

150 cases of salmonellosis 224,000 affected persons nationwide



Multi-state oubreak of Salmonella Muenchen in 15 states and 2 Canadian provinces. Associated with fresh orange juice

More than 300 cases reported



Multi-state outbreak caused by Salmonella Typhimurium that contaminated peanut butter and peanut paste

Firm recalled many of its products, including 1,700-pound tanker containers, because the products had the potential to be cross-contaminated with Salmonella during transport



Based on data, regulations have been implemented to prevent food contamination from nonfood sources and prescribe sanitary transportation practices to be followed by shippers, carriers by motor vehicle or rail vehicle, receivers, and other persons engaged in transportation of food (3).





3. Hennessy T.W., Hedberg, C.W., Slutsker, L. et al., 1996, ‘‘A National Outbreak of Salmonella Enteriditis Infections From Ice Cream,’’ New England Journal of Medicine, Vol. 334, No. 20, pp. 1281–1286.