Food Safety Part I: Foods to Avoid at Your Next Holiday Potluck

Nov. 21, 2018

While the holiday season is known for being the busiest, most traveled, and most expensive time of year, it is also the heaviest, as we indulge in rich, festive foods, from turkey in November to champagne in January. As many of us look forward to meals shared with friends and family, unwelcome microbes can lurk in the shadows (or in the stuffing), waiting for an opportunity to crash your party. Foodborne illness can certainly spoil the holiday fun.
 
When pathogenic microbes, such as Salmonella, find their way into foods, they can replicate and/or produce toxins that irritate your stomach and make you sick. Though they are often used interchangeably, foodborne illness differs from food poisoning, as foodborne illness is characterized by infection, and food poisoning occurs as a result of microbial toxins in food. The symptoms of foodborne illness may not appear immediately, and those affected often present with vomiting, fever, diarrhea, and muscle aches 24-48 hours following ingestion and can last for several days. Organisms such as Salmonella typically cause foodborne illness via replication, causing gastrointestinal infection and occasionally, can progress into more severe infections such as bacteremia. Food poisoning can have similar symptoms, depending on the toxin, but it usually develops within 1-6 hours and resolves quickly. Botulism is an example of food poisoning, as the botulinum toxin, rather than the bacteria that produces it (Clostridium botulinum) causes rapid
 
While most cases are self-limiting and resolve in a few days, in some circumstances, both foodborne illness and food poisoning can cause death. Foodborne illness causes an estimated 48 million illnesses, 128,000 hospitalizations, and 3,000 deaths in the United States annually. Mortality primarily occurs in young children, the elderly, and the immunosuppressed, but healthy adults have also succumbed to food poisoning due to highly potent toxins, such as Shiga toxin, which can cause hemorrhagic diarrhea and kidney failure.
 
The holiday season brings particular risk for becoming sick, as some popular foods are known for harboring illness-causing microbes if not handled carefully. The ongoing Salmonella outbreak affecting turkey products and a romaine lettuce Escherichia coli outbreak, announced earlier this week, are particularly poorly timed. The Salmonella outbreak  has already sickened 164 people in 35 states, and the E. coli outbreak has sickened 32 people in 11 states. These outbreaks leave many people at risk throughout the holidays. Despite the risk, If you know what foods to avoid and use time and temperature precautions in the kitchen, you will be more likely to prevent food-related illness from occuring.


High-Risk Foods and the Microbes that Love Them

Foodborne illness was prevalent in 2018, with 21 outbreaks listed on the CDC webpage as of November 2018.
 
Affected food products from throughout this year include:
 
Category Product
Animal-origin Chicken, beef, ham, turkey, crab, eggs
Produce Melon, salad mix, romaine lettuce, coconut, sprouts
Ready-to-eat foods Pasta salads, cereal, vegetable trays

Over 70% of the outbreaks this year were caused by Salmonella species. Other pathogens implicated in outbreaks this year include Listeria monocytogenes, 2 hemorrhagic serotypes of E. coli (O26; O157:H7), Vibrio parahaemolyticus, and Cyclospora cayetanensis—the lone parasite and only non-bacterial organism on the list.The CDC lists several food categories as frequently associated with illness that appear often in recalls and outbreaks. In general, while any food that becomes contaminated during production and/or handling can make you sick, produce and foods of animal origin are most commonly associated with food poisoning. Below are some specific foods to watch out for this holiday season.
 

Holiday Foods to Beware 

 
USDA recommendations for storing leftovers.
  • Eggnog made with unpasteurized eggs: Most store-bought varieties of eggnog are pasteurized and present less risk of causing food-bourne illness. If you make your own, make sure the eggs are pasteurized. Be aware that even if your eggs are pasteurized, leaving the eggnog out of the fridge for too long, or drinking it past its expiration date, might still get you sick.
  • Unpasteurized cider: Dangerous microbes could be present on the outside or inside of produce used in ciders, winding up in your beverage. As is the case with eggnog, most store-bought products will be pasteurized unless otherwise stated. Unpasteurized cider should be refrigerated and bear a warning label, informing consumers of the risks of unpasteurized juices.
  • Cookie dough: Make sure Santa’s cookies are thoroughly cooked, as uncooked cookie dough contains raw flour, as well as raw eggs. Contrary to popular belief, raw flour is the primary concern in cookie dough, as it can become contaminated with shiga toxin-producing E. coli during milling.
  • Undercooked meat: Food thermometers are an essential tool to ensure that meat has reached the proper temperature. For all of your meat, poultry, and egg product safety questions, the United States Department of Agriculture (USDA) has set up a free Meat and Poultry Hotline (1-888-MPHotline). While you’re prepping your turkey, don’t wash it in the sink, as this only contaminates your cooking area, without removing bacteria from the turkey. This “do not wash” rule applies to chicken as well.
  • Stuffing: Cooking stuffing inside the turkey can be problematic, as both the stuffing and the turkey may not reach safe temperatures, allowing microbes to thrive. As some types of stuffing contain raw meat, such as sausage, it is vital that the stuffing is cooked properly. It is safest to cook stuffing in a casserole dish outside of the turkey, and the USDA recommends not stuffing your turkey. However, if you must stuff, the safest way is to cook and stuff the stuffing immediately prior to cooking the turkey, while the stuffing is still hot. Another option is to stuff the turkey beneath the skin, which will reach a higher temperature. It is essential to use a food thermometer (in multiple areas of the turkey and stuffing) to assure that both the stuffing and turkey have reached safe temperatures, so that the stuffing does not harbor residual bacteria from the turkey.
  • Leftovers: Leftovers are a staple of any holiday feast, and some say, they taste even better than the main meal itself. But even if you washed and prepared food correctly, if food is stored improperly, Staphylococcus aureus and the hardy, spore-forming Clostridium perfringens might stick around for the afterparty. Leftovers must be refrigerated within 2 hours, and shallow storage containers help to speed up the cooling process, so that your food spends less time at the unsafe temperatures that promote bacterial growth.

The Danger Zone 

In many cases, if bacteria are present in food, the food must remain at certain temperatures for an extended period of time for the number of bacteria to become dangerous. At temperatures between 40 and 140°F, bacteria can grow rapidly, doubling in less than 20 minutes. This temperature range is commonly referred to as “the danger zone.” The USDA has established optimal minimum cooking temperatures for meat, seafood, and poultry, in particular, as these animal-based foods present high risk of contamination. For example, all poultry must reach a minimum internal temperature of 165°F, whereas steaks and roasts must reach at least 145°F.
USDA recommendations for cooking a turkey.
 
While refrigeration slows down growth for most foodborne pathogens, L. monocytogenes is more challenging to prevent, as it can survive and even grow at temperatures below 33°F. Foods that commonly harbor L. monocytogenes include hot dogs, deli meat, soft cheeses, and raw produce.While many people are asymptomatic and may only feel mild malaise from a listeria infection, pregnant women and their fetuses, as well as elderly and/or immunosuppressed patients, can suffer extreme consequences, ranging from miscarriage to sepsis.
 
The relationship between time and temperature is critically important for maintaining food safety. Live bacteria can produce toxins and spores, and while cooking foods can eliminate live bacteria, the toxins and spores can remain intact, even at high temperatures. The more time the food is given to sit at an unsafe temperature, the more spores and toxin can be produced. For example, Bacillus cereus spores are a prevalent contaminant of rice that has been stored improperly and reheated. Spores present in the uncooked rice can survive boiling, and then reproduce in unrefrigerated cooked rice. The reproducing bacteria then produce enterotoxins that are resistant to heat, rendering the rice unsafe even upon re-heating.

How do government scientists use novel technologies and approaches that government scientists use to identify, track down, and maintain foodborne outbreaks? Stay tuned for Part II of this series on Food Safety.
 
Further Reading:
Gene Transfer: How You Really Got That Stomach Bug
FDA’s Bad Bug Book: Handbook of Foodborne Pathogenic Microorganisms and Natural Toxins
Foodborne Illness Acquired in the United States—Major Pathogens
Food Leftover Practices among Consumers in Selected Countries in Europe, South and North America

Author: Rita Algorri

Rita Algorri
Rita Algorri is a freelance writer, Ph.D. candidate in Clinical and Experimental Therapeutics, and Master's student in Regulatory Science at the University of Southern California.