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The fourth Thursday of November marks the annual tradition in the U.S. called Thanksgiving. Originally, Thanksgiving was a religious holiday that has sinced turned secular and became a national holiday in 1941. Now, for families celebrating Thanskgiving, it is a time to cook a whole lot of food and eat way too much pumpkin pie.
But if you undercook, cross-contaminate, or improperly store your food you can get some pretty interesting microbiology going on. After all, pumpkin pie is full of sugars, protein, and fats- everything that a lovely swarm of bacteria also enjoys as a midnight snack.
So let's take a seasonal look at what you could be growing in your Thanksgiving dinner, and how you can prevent growing it to ensure the celebrations pass with no ill-effects.
So what are the sources of bacterial contamination in food?
1. The Animal
Microbes are everywhere in our environment and on our bodies so there are many opportunities for bacteria to infect sources of food. In the case of beef and poultry, the microorganisms are often found in the intestines of healthy animals and are spread during slaughter. Fruits and vegetables may become infected when they are washed or irrigated with water contaminated with animal manure. Salmonella can infect the hen egg before it is formed so the egg can be contaminated (which is why you shouldn't eat raw cookie dough!)
2. Food Handlers
Some types of microbial pathogens can be passed on to your food via the staff working in the kitchen (sorry, Mom. This includes you). Shigella and some viruses (Norwalk and Hepatits A) come from human contact with food. Another source is using cutlery on raw foods and not cleaning them before re-using. Similarly, cutting boards and utensils used for handling raw food need to be cleaned before use. Even if the food was cooked, the contamination can be reintroduced with contact with surfaces or drippings from raw or contaminated food.
Most likely, mom and her helpers in the kitchen all washed their hands and the utensils after handling the raw turkey and moving on to the mashed potatoes or cranberry sauce. So another source of food poisoning is by simply not storing the cooked food properly once it has cooled down. That's right- the leftovers! Make sure to store your leftover food correctly so bacteria that may be present from the environment and the little kids hands isn't allowed to flourish.
What are the best storage temperatures? According to the Arizona Dept. of Health, food should be stored at 34 to 40°F (1 to 3°C). Above 3°C foods will spoil rapidly. Frozen food should be kept at 0°F (-17°C). The temperature should not reach higher than 5°F (-15°C). Check the temperature with a thermometer, or use this rule of thumb: If the freezer can't keep ice cream brick-solid, the temperature is above the recommended level. Some additional food storage tips can be found on the Santa Barbara Dept. of public health website also.
What critters should you watch out for?
Now let's discuss the bacteria that can cause the post-celebration blues. What are the most typical pathogens that infect foods, both pre and post cooking? Based on statistics collected by the CDC between the years of 1983 and 1997, Campylobacter spp. contamination resulted in the majority of bacterially caused food borne illnesses (2.4 million cases, almost 50%) followed by non-typhoidal Salmonella (1.4 million cases). However, there can be a high degree of under-reporting in bacterial infections because not everyone will go to a hospital when they are sick. The level of under-reporting for Salmonella is estimated at ~38 fold and for E.coli (0157:H7), ~20 fold. However, Norwalk viruses caused far more food-borne illness, approximately 23 million cases out of a total of 30 million.
Name that Food Pathogen
The following information comes from the Iowa State Food Safety website. The symptoms of all of these are very similar. You can pretty much count on having abdominal cramps and diarrhea if you become infected with any of these microorganisms and for some, add in vomiting:
Escherichia coli 0157:H7
Norwalk, Norwalk-like, or norovirus
Make sure the critters don't get you this year…
As you can see, proper food handling and storage is serious business. But prevention is simple; don't eat raw chicken, clean cutlery and counters between handling raw meats, wash your hands after using the bathroom, wash your hands after changing a diaper, don't sneeze on food and then leave it out on the counter all night, and make sure you have a half-gallon block of ice cream in your freezer that is frozen solid (as a measure of how well your freezer is working).
Joking aside, getting sick on your vacation is not fun or a safe way of losing the extra holiday pounds. So use common sense and enjoy a hot and tasty meal with all the trimmings and the leftovers too.
Thanks for reading and please leave us a comment if you have more food safety advice or a personal experience involving food-borne pathogens you'd like to share.
More information on foodborne illness can be found at the CDC's website.