How Food Becomes Contaminated

According to the U.S. Centers for Disease Control and Prevention (CDC), food can become a source of illness when it is contaminated with pathogens from human or animal waste, or when it is exposed to temperatures suitable for microbial growth for extended periods. Some potential pathogens are harmless if the food is properly cooked and stored at the correct temperature. However, cross-contamination is another transmission route, for example, using a knife or cutting board that has handled raw meat, which then contaminates other foods. Additionally, if food handlers have cuts on their hands or cough on food, they can spread bacteria like Staphylococcus aureus. While many pathogens can be killed by heating, if food is exposed to unsafe temperatures, microorganisms can produce toxins that may not be eliminated by cooking.

About Food Poisoning

The CDC estimates that about one in six Americans gets sick from foodborne diseases each year. The most common culprits are pathogenic bacteria and viruses, but parasites, fungi, natural food toxins, and even heavy metals can also be the cause. Because soy milk is thoroughly heated before being made into tofu, killing most of the bacteria and viruses in the soybeans, properly processed and handled tofu has a relatively low risk of contamination.

Potential Pathways for Tofu Contamination

Although uncommon, there are several ways tofu can lead to foodborne illness. One is contamination from the tofu itself, such as from unclean equipment in a food processing plant. Secondly, tofu can be contaminated by food handlers who have not washed their hands, sneezed or coughed on the food, or come into contact with pathogens from other foods like raw chicken. Tofu can also be exposed to pathogens if stored in contaminated water. The safety risk is particularly high when buying bulk tofu (sold from large water tanks), as unwashed hands or unclean water can infect the entire batch.

Ensuring Tofu Safety

To minimize the risk of food poisoning, be sure to follow these safety guidelines:

• Follow Packaging Instructions: Always store tofu according to the instructions on the product packaging. Some tofu can be stored at room temperature before opening but requires refrigeration after. Many tofu products are sold refrigerated in individual water-filled packages.
• Choose Reputable Sources: If buying bulk tofu, choose a reputable vendor and ask about their production batches and how often they change the water.
• Use Clean Utensils: When preparing tofu, use clean utensils and containers to avoid cross-contamination.
• Refrigerate Properly: Leftover tofu should be refrigerated immediately, as bacteria grow fastest in the "danger zone" between 5°C and 60°C (40°F and 140°F).