Although summer is winding down for many of us, there are still ample opportunities for outdoor cooking and eating events as we head into fall. Many of us will have one last pool party of the season on Labor Day weekend. After that, football season will begin and, for many of us, that means tailgating. In order to ensure that a good time is had by all, I thought it would be a good time to discuss food safety. It’s also very timely since I recently had a bout with food poisoning. If this write-up prevents at least one person from getting food poisoning, it will have been time well-spent in putting it together.
Here’s the scenario that I just recovered from…A friend of mine picked up some BBQ (brisket). After having dinner, we divided up what was left for future meals. About 4-5 hours after dinner, I felt a bit queasy but it quickly passed and I didn't give it a second thought – I chalked it up to having an off-day. Two days later, I had more of the remaining brisket. Turned out not to be a good thing. Like the first night, I began to not feel good about 5 hours later. I didn't get off so easy the second time around. The next 24 hours or so were dismal. Was literally up all night and felt miserable the next day. I then called my friend and he experienced the same thing. Much as I hated to, I tossed the remaining brisket. Although I didn't know it at the time, I later found out that my friend (not one of my tailgating buddies who would have known better) picked up the brisket and then did several errands before we met up. All the while, the brisket had sat in the car for a few hours between when he picked it up and when we dug into it, even though it still seemed warm. As the brisket sat in my friend’s car for around 3 hours at temperatures averaging between 90° and 100°F, the brisket cooled off just enough, and for a long-enough period of time, to become a target for bacteria to set up shop and proliferate.
Traditional BBQ, especially brisket, pulled pork, and ribs are among the safer items at a cookout since they are cooked/smoked to high internal temperature (around 200°F) and then held there for several hours to make them tender. This temperature is much above the temperature where bacteria are instantly killed off and food is considered safe per FDA guidelines (e.g., 165°F). So you may be curious as to how meat cooked to such a high internal temperature for so long could become contaminated. Well, we need to delve into a little microbiology to find the answer – I’ll keep it simple, I promise!
When we think of bacteria, we are usually referring to the “vegetative” state. This is the living state where the cells divide and multiply rapidly. In the case of bad bacteria, this rapid multiplication and the toxins they produce is what causes illnesses like food poisoning. Some bacteria can morph into a second state called an endospore (a.k.a., spore). This happens when the environment becomes hostile for the bacterium to proliferate in the vegetative state. The spore is a dormant state that allows the bacterium to survive more hostile conditions (such as some cooking environments) in a “stripped-down” form compared to the vegetative state. Spores can be found in food, air, water, and soil. While in spore form, bacterium do not divide and multiply like they do in the vegetative state. When the environment becomes more favorable to the bacterium, the spore can regenerate back into the vegetative state and multiply. The good news for us is that the process of going from the vegetative state to spore and vice-versa takes some time – several hours depending on the type of bacteria and the environment. This can be used to our advantage during the cooking process and it gives us some lead time to pack up and store leftovers down below 40°F before any spores can regenerate.
The above process illustrates how even properly cooked meats can become contaminated through improper handling and holding. If food is left out for a sufficiently long time before serving, or if it is left on the table for people to nibble on later, the meat can cool into the heart of the “Bacterial Danger Zone” of 40-140°F or 4-60°C. If it is allowed to stay within that temperature range for a long-enough period of time, it will permit any spores that may have survived the cooking process to regenerate into the vegetative state and contaminate the food.
A few general tips on avoiding food poisoning:
- Don’t thaw meat on the counter at room temperature– ever! In fact, when I cook burgers, I place them frozen on a preheated grill. I don't notice much difference in the cooking time and I think they come out better vs. thawed.
- Cook foods to the proper temperature. For grilled chicken and ground beef, this means an internal temperature of 165°F / 74°C. Use a good digital thermometer to confirm.
- If you are doing traditional smoked BBQ, you will cook the meat to an internal temperature well in excess of 165°F, so no worries about under-cooking. However, I would strongly suggest maintaining the temperature of your smoker to at least 225°F while the meat is cooking. Depending on what I’m BBQ’ing, I have been known to start the BBQ cook with the smoker at 300-350°F and let it gradually come down to 225-250°F or so for the duration of the cook. This gives the raw meat an initial blast of heat to minimize the time that the interior of the meat is below 140°F. It will also kill off more bacteria while in the easier-to-kill vegetative state before they have time to morph into spores and it increases the likelihood that any spores present on the surface of the meat prior to cooking will be killed at this higher temperature. It also sets the stage for a firmer bark on the meat which I prefer.
- While serving, keep hot food above 140°F / 60°C and cold food below 40°F / 4°C. This is not limited to meat products. An often-overlooked source of food poisoning are sauces (e.g., BBQ sauce and bastes) especially those containing meat drippings . Here’s a typical scenario: You decide to use some marinade or BBQ sauce as a baste or finish dressing. Even if the sauce/baste was first brought to a boil or to “bubbling”, some spores that were present within might survive. If it is allowed to cool to ambient air temperature, any surviving spores could “hatch” in the cup of basting sauce you’ve had sitting next to the grill for a few hours and that you just applied to the meat.
- Cool down, as quickly as possible, leftover hot foods after eating: The FDA requires food processors to get the temperature of hot food down to 41°F in six hours. This assumes the food has been sitting at room temperature (~70°F). In an outdoor event where the temperature is often at or above 80F°, you have less time since biological processes happen much faster at these temperatures. If you do not have a reliable way to keep hot foods above 140°F during the entire serving time, I would make a “last-call” after about one hour of the food being removed from the cooking source. Recall that even if spores are present, it will take several hours to regenerate into vegetative bacteria if the food temperature gets into the Danger Zone of 40-140°F, so you do have some lead time. After “last call”, take any leftovers and put them in large zipper-type freezer bags. Then place them in ice, preferably in a separate cooler from beverages. This will quickly cool the food down below 40°F. When you get home, place these items in the fridge or freezer.
I know this question will come up: How is it that I can eat a steak (filet, NY strip, porterhouse, etc.) rare or medium-rare that is cooked to an internal temperature of 125-135°F and have it be safe? Well, there’s always a slight risk with anything. However, microbes do not penetrate whole muscle meats very well, so the interior of a fresh steak is pretty safe. Since these type of steaks are usually cooked directly over the heat source and at a much higher temperature compared to slow-roasted BBQ, all vegetative bacteria and virtually all spores on the surface are killed almost instantly by the heat of cooking. Just note that even with these steaks, they can become contaminated if left out too long after cooking unless they are kept at 140°F or higher. Just avoid any steaks that have been “blade-tenderized” which involves stabbing the meat with a sharp instrument such as a fork or jaccard. This process is sometimes used on tougher cuts of meat. The intent is to pierce the tough connective tissue to make the meat more tender. This will also push any surface bacteria towards the center of the meat and increase the risk of contamination.