CSU's The Audit

INTRO: Welcome to Colorado State University's podcast, The Audit, where host Stacy Nick talks with CSU faculty about topics ranging from their latest research to current events.

HOST INTRO: As Thanksgiving approaches, the mind wanders to many things – the food, the family get-togethers, the leftovers.

That last one can be tricky. Exactly how long can you keep feasting after the big day, without getting a big case of food poisoning?

To find out, we spoke with Brad Reisfeld, a toxicologist and researcher specializing in how foreign chemicals – such as those released during food spoilage – affect the body. A CSU emeritus professor of chemical and biological engineering, biomedical engineering, and public health, Reisfeld recently published a piece on the topic in The Conversation.

HOST: I'm just going to dive in and ask what at the Thanksgiving table is safer for me to take a chance when it comes to lingering leftovers and what should be a no-go if it seems a little iffy.

REISFELD: Well, that's a great question. I love Thanksgiving, the celebration, and I especially love leftovers. The main thing I think to keep in mind is that as soon as you can or when there are breaks in your celebration put things in the fridge and make sure that they're at a cold temperature so things like bacteria don't tend to grow as quickly. In terms of what might be safer, there are some kinds of foods that are a little bit more resistant to bacterial growth. So, things like your cranberry sauce, which has a little acid in it, help in terms of delaying bacteria. Things like if you roast vegetables, stuff like that. Fruit pies are probably another one where they're relatively resistant. Rolls and bread, things like that, will go longer. They may go stale, but they're not going to really get too nasty. On the other side of the coin, you'll want to make sure that you sort of trim away the turkey, if you have turkey or whatever meat, if you have meat, from the bone, and then store it as just pieces of meat, preferably without gravy or anything on it. Gravy, stuffing that's cooked inside the bird; those may tend to go bad a little bit more quickly. Things with dairy or eggs may also go bad a little more quickly so again if you can refrigerate things, they're going to stay good for quite a while, but those are some of the sorts of things. Obviously use your senses as you examine your leftovers - if things begin to smell funky, look odd, use your judgment. Evolution has provided us with these great tools for evaluating food safety on our own. So, use your judgment. And when in doubt, throw it out. It's not worth the health risk.

HOST: So, let's talk a little bit about some of those health risks. In your Conversation piece, you mentioned spoiled meat may seem like a thing that people are most concerned about. That's kind of the big one that I think about first and that we hear about most in relation to severe illnesses and even death due to reports of salmonella or E. Coli. Making sure that meat is well cooked is obviously important, but is it a fail safe? There're times where you think, well, it's a little past the date, but if I cook it really well, maybe it's okay.

REISFELD: No, I mean, I think it's a common way of thinking because we're told as long as you cook your meat to an internal temperature of 160, 165 degrees, it will be safe. The problem is that we get ill not only from the bacteria - so something like salmonella is going to cause its bad health effects because of the bacteria itself. Not only do the bacteria cause illnesses, but the byproducts that the bacteria produce do as well. There're certain toxins that are produced by bacteria. There's a kind of E. Coli that causes health problems, and a lot of those are due to the toxins that are released. And unfortunately, a lot of those toxins are what we would call heat stable, which means that they'll survive cooking at the temperatures that we would normally use in our oven. So, regarding meat, it's not fail safe to just cook meat beyond that, especially if it's sort of in a questionable state. The best advice, again, is to look at it. Is it starting to look off? Does it smell different than when you bought it? Is the texture weird? Is it starting to get slimy? Those are all clues that something's going on in terms of biology and that things might be growing on your food. Aside from that, I think even if you cook it and it's safe, I don't imagine it would necessarily taste great. So again, if there's questions about it, my advice would be to pitch it. You want to also make sure that you thaw meat properly. Don't just leave it out on the counter for a day or two. Thaw it in your refrigerator or sometimes cold water's a way to do it as well. So unfortunately, we have these chemicals and other things that are produced in the process of food spoiling that can add to the mix in terms of health concerns.

HOST: Is meat the worst thing? That's the thing that we always hear about.

REISFELD: It's not the most dangerous, but I think in terms of events that happen in our food supply, those are the ones that seem to gain a lot of traction. We also hear about salmonella on lettuce or whatever it might be. Those get a lot of attention also. We've just heard recently about some food recalls. Meat, in terms of the adverse health effects, can be quite severe. There are some chemicals that can be produced from different things in food that can be a little bit more potent, and those are things to be aware of as well. But meat is definitely at the forefront of a lot of people's thinking.

HOST: One of the things you also wrote about was plant-based foods, such as grains and nuts. It sounds like mold can produce some pretty nasty toxins that can damage the liver, and that may even be linked to liver cancer.

REISFELD: Yep, and again, this isn't meant to scare anybody. But when certain plants are grown at high temperatures and high humidities, especially when there's drought conditions, they're susceptible to having fungus attack them and invade them. So, what can happen, at least in some of those cases, is that you'll get mold growing on them, and these molds can produce these byproducts that can be toxic. In the case of certain cereals and grains, meaning like corn, rice, nuts, there's several kinds of molds that produce a chemical called aflatoxin, which is a very potent toxin that's been associated with liver cancer and liver damage. The way that you might detect it is that the molds that produce those would be green, maybe a light green or a dark green. They may be kind of fuzzy. Anytime you see any kind of mold growing on grains or nuts, I would just pitch it because you don't really know. Just by looking at it, what kind of things might be produced by the microorganism. However, the food supply in the U.S. is pretty safe. Farmers and the inspectors for the government do their best to keep these out of the food supply. They have to get rid of tons of these kinds of crops because they do get these fungi on them. But it's good to just be aware that they can crop up even if they're infrequent. And with aflatoxins, again, they're very potent, and we want to just make sure that everybody stays safe. Unfortunately, even if your naked eye doesn't pick up on it, sometimes these things can still be in your food, but I would say just be aware and don't be overly cavalier if you do see mold on crops like these on rice or nuts or things like that.

HOST: Is there a level that we should be thinking of? I mean, is it a little dangerous or would you have to eat a lot?

REISFELD: That's a tough one because everybody has a different tolerance for things. With aflatoxins, again, they're very potent, so I really wouldn't say that there's necessarily a safe dosage of those for everybody. I think it's really an individual thing, and you don't really even know how much of the toxin might be in the product at all. So, it's really hard to know what might be safe to eat. I'd say just be sort of cautious but again, not overly panicked, about these kinds of things.

HOST: That made me think of, I have a friend whose dad, her entire childhood, was always chancing stuff. And she credits his cooking with her making it through a lot of traveling around the world with no stomach issues at all. Can you build up a tolerance? Are there people that are basically immune to food poisoning?

REISFELD: I think some people have a constitution or their biochemistry is such that they're more resistant. You can build up a tolerance to certain kinds of allergens or other kinds of chemical assaults on your body. I don't know that I would recommend a diet that's constantly making you sick just to prepare for a trip overseas, but I think there's some validity in exposing yourself to things, and not being overly cautious about eating just because it limits the variety of foods you experience and may also limit your ability to deal with something if it comes along.

HOST: One of the things that I think we consider usually the safest food is fruit, and I think that's also one of those that's tough for a lot of people because fruit's expensive and no one wants to throw out a peach or berries. Especially if you have little ones, they eat a lot of fruit. I've definitely cut a yucky bit off of a piece of fruit or picked through a container of blueberries and tossed out the fuzzy ones and eaten the others. Is that safe?

REISFELD: That's a great point. I think most of us were raised to think that food is precious and it's a scarce resource, and we don't want to waste it. I'm fully on board with that. In terms of let's say you have some spoiled berries in a package, in my opinion take a look at them if there's some that seem to have their original texture and things like that, I think I would probably be comfortable with eating those and pitching the others. It's not only your visual impression, but it's also your sense of touch that can offer clues. Is it getting mushy? Does it seem much different than when you bought it? In terms of a piece of fruit, especially for a harder fruit like an apple or something, I think cutting around a spot is fine and eating the rest. If you have something like a tomato, I would be less comfortable with that because the mold that grows on there sends out these little hyphae; they're kind of like root structures into the fruit and that's what it uses to break down the fruit or vegetable. So, there's a lot going on under the surface. You can't just scrape off the moldy part because that's really not the part to be concerned about. It's what's under the surface. So, for something that's softer or juicier, I would probably just compost it and not chance it. But I think there's no need to throw out the whole container if it looks like there's just limited mold spots. Just recognize that probably if there's some mold, there may be a little bit on others even if you can't see it.

HOST: A little mold is not so bad.

REISFELD: Yes. Unless you have an allergy, I don't see there being a big health risk.

HOST: Then on the complete other end of the spectrum, we have cheese, which is actually a byproduct of mold, right? So, what makes this mold different, and when does it become problematic?

REISFELD: Actually, as a hobby, I make cheese. So, as you make cheese, you intentionally introduce certain yeasts and certain molds to give the cheese its characteristic flavor or texture or aroma, and those kinds of particular strains of mold and yeast are known to not cause health problems. They'll impart the rind that you might see on a brie cheese, or they might give you the veins that you see in a Roquefort or a blue cheese or give you maybe an aroma that's distinctive. These are the intentional molds that we introduce to impart certain characteristics. Then there's ones that are unintentional, and those are the ones that are floating around in the air all the time and will settle on cheese and then begin to grow. But not all of those are necessarily too problematic either. Some of them are a little bit nastier than others. If you see mold on a cheese that doesn't normally have mold, like a cheddar or something, or if the mold is in patches, and fuzzy, those are telltale signs, that it's not an intentional mold. If you have mold that are black or pink, or even red, those are not things you should be eating. In those cases, if you have a hard cheese, cutting out where the mold occurs and eating the rest is fine. With softer cheeses, you'll get more internal growth, so those might be slightly more iffy. Especially something like cottage cheese, if you have a mold spot it may have penetrated further into it. If the texture, the look, the smell are significantly different than when you bought it, or if it has an ammonia smell – things like that are definitely not a good thing.

HOST: So, there's good stinky cheese and bad stinky cheese.

REISFELD: Yeah, yeah, and it would be hard to know, I guess, if you had a Limburger or something, you're used to sort of the pungency, but if you get that in your cheddar, again it's probably not a good thing.

HOST: We've been talking a lot about using your senses, but you know, there are folks that very strictly adhere to the best by or expiration dates. That's what they live and die by, maybe literally. And then there are those that push things a week or two - or a month or five, depending on the item. And typically, those two people marry each other. I am speaking from experience here. What are some basic things to take into consideration when you're in a battle with your spouse about whether to keep or toss something?

REISFELD: Not to add to people's marital discord or cause any controversy, but one thing to keep in mind is that with the exception of infant formula, the best used by or the used by dates are from the manufacturer. They're not from the government. They indicate quality. They don't indicate safety. The manufacturers will take their product and put it in some environment that the consumer might experience, and then they'll test it periodically to see if it's deviated from what they think is a quality product. So, the texture might change, and the smell might change. But that doesn't necessarily indicate that there's any sort of safety concern. Those dates are a sort of guideline, but they're not something that you necessarily should look at as, when we reach the best use by date, we need to chuck it. I'm in the camp of, again, using your senses and how did the product look when I bought it, is it different, is it have some of these telltale signs of mold such as funky smells. The best used by date might be a very rough guideline of when you start looking at an item a little more carefully, but it wouldn't be a date where I would begin to pitch things.

HOST: See that? I was right.

REISFELD: Glad I could help.

HOST: So, as an expert on molds and food toxins, I'm wondering, when was the last time you got food poisoning, if you don't mind me asking?

REISFELD: No, that's fine. What you were saying earlier about your friend not getting food poisoning while travelling reminds me of the time I had spent in Thailand. I was there for about a year and during that period I was eating at the food commons for the university, and something got me at that point and it was it was a pretty intense experience, so I guess my system hadn't seen that particular bacterium or whatever before. But it's been a while. However, I love to try foods when I travel, and so, it didn't stop me once I recovered. I think that it's not uncommon for people to experience when their system is not necessarily used to what's on the food wherever they are.

HOST: And different countries have different ways of storing food. I mean, in Europe, they'll put milk and butter out, and that sounds horrible to us.

REISFELD: Yeah, you would see practices in Thailand that were very different in the way that food such as fish would be left out where you'd see them in a freezer or refrigerator case here. But it's not something reckless. It's obviously been fine for generations of people who live there. It's just different. I was just reading something about eggs. The question was about why do Americans store their eggs in refrigerators, whereas almost everywhere else they don't? And it really comes down to the fact that in our normal food supply, our eggs get washed thoroughly, and it removes the protective covering that's on the eggs that prevents things like salmonella from entering them. So, in this country, it's a reasonable practice to wash them. But if you have fresh eggs, it's usually not needed. I think what you're raised on is going to be comfortable, and people who come into that environment may have some different issues in terms of their tolerance for your food.

HOST: But don't eat the spoiled meat.

REISFELD: I would say no, do not eat the spoiled meat.

HOST: Alright, well thank you so much for being here, I really appreciate your time.

REISFELD: Thanks Stacy, thanks for inviting me.

OUTRO: That was toxicologist Brad Reisfeld, talking about the food safety impacts of mold. I’m your host, Stacy Nick, and you’re listening to CSU’s The Audit.