Food safety and the coronavirus with food science writer J. Kenji López-Alt

There are a lot of questions and concerns right now around the coronavirus and the safety of our food. The science behind all of this is an everchanging field of study, but we wanted to learn the current findings and recommendations for keeping safe not only with home-cooked food and delivery, but also when out in public shopping for food and grabbing take-out from restaurants. We learned a lot from food science writer J. Kenji López-Alt. He is the Chief Culinary Advisor of Serious Eats and the author of The Food Lab: Better Home Cooking Through Science. He and Francis Lam spoke about the unfolding situation.

J. Kenji López-Alt's upcoming second book is an illustrated children's book. Every Night is Pizza Night will be released on September 1st. Currently, Kenji is donating 100% of his sales commissions from books purchased or pre-ordered through his bookshop.org page. As mentioned in the interview below, he is also raising money to provide free meals to frontline workers and those in need in the San Francisco Bay Area. Ongoing monthly donations can be made through his Patreon page, where 100 percent of donations will go directly to producing and distributing free meals.

Francis Lam: First of all, I want to thank you for the incredible piece you wrote for Serious Eats, Food Safety and Coronavirus: A Comprehensive Guide. In this moment I think a lot of people have a lot of questions about what is safe to eat, what’s not safe to eat, how to handle themselves in the store, is restaurant food okay even though a lot of restaurants have moved to delivery or take-out. But first I want to ask you, how are you doing?

J. Kenji López-Alt: We’re doing alright, taking it day-by-day. The restaurant [Wursthall (a San Mateo beer hall)] obviously took a huge hit just as every restaurant in the world right now is doing. We’ve had to shut down dine-in service, so we’re take-out only. And what I’ve been working on recently is a initiative to get some of our people, our hourly workers, back into work by cooking meals for people who need them - like first responders and emergency room personnel. People who are already food insecure to begin with are even worse off now, so we’re trying to use all the resources at the restaurant to get meals out to those people while accepting donations to produce those meals with the idea that we’ll be able to keep our employees more busy going forward while also doing good for the community.

It’s tough though, you know. A lot of people are scared about what they can eat, what they can be doing, what they can’t be doing, whether they can cook for themselves, whether they should go shopping at the supermarket, all that stuff. I think a lot of people just planned assuming for the worst and went out and bought three months of supplies, three months worth of toilet paper. So, the dining and take-out crowd has gone down quite a bit across the industry. We’re trying to build that back up and make sure that when things do go back to normal that people will still have a restaurant to come back to. I think we’re going to see a lot of closures in the service industry because most restaurants don’t have the runway to lose a week of sales, let alone three months of sales or however long this is going to end up being. I think everyone in the industry is trying to get creative and we’re all just doing our best.

CORONAVIRUS EFFECT ON THE RESTAURANT INDUSTRY

FL: I definitely want to get into what we can do as regular people in terms of everyone shopping and cooking. But first, I do think this is a cataclysmic event for an industry that brings people so much joy in normal times and sustenance. The one thing I do see that gives me some glimmer of hope or humanity is seeing how many restaurants are doing things like yours. They’re saying, okay, we can’t serve the public, but let’s do what we can for each other, cooking for unemployed restaurant workers and cooking for first responders. It’s an industry made of people who want to take care of each other – and I really see that now.

JKLA: It’s also been great seeing the numbers of people who are offering their support to us, some of it financially. We have more people who want to donate money to us right now than we have methods to receive it. People in Tennessee have been like, I want to give you money, how can I do that? And we don’t really have a way to do that yet, but we’re going to try to get it set up. It’s like we’re building the plane as we’re flying it and everything is just sort of ad hoc as we go. Systems are getting put in place and it’s just been amazing how many people are willing to do good when times get tough. There’s a lot of good people out there, which is great to see.

HOW IS THE VIRUS TRANSMITTED?

FL: Let’s talk about the virus and your research on the food safety at this moment. I think first we have to caveat everything by saying there’s a lot that scientists don’t know about the virus and what causes COVID-19. There’s new research literally every day. But, scientists do generally believe it’s primarily transmitted person-to-person. Right, not by incidental contact with stuff.

JKLA: Correct.

FL: But, there is a theoretical risk anyway of touching stuff that a sick person might have sneezed on and then getting that into our system. Given that, it does sound like food could be a way of getting infected, right?

JKLA: Well, it is a novel virus like you said. We’re still doing research on it. There’s always a possibility, of course, but what we do know for certain is by far the majority of cases – in fact every case we’ve found so far or every case we’ve tracked so far – none have been linked to food or packaging or any kind of fomite is what it’s called, when it gets on something, gets on a solid object and is transferred to a person that way. All of the spread patterns we’ve seen have been based on aerosolized or droplet forms. Basically, when someone sneezes or coughs or breathes very moist air, viral load can get into that moisture, into the air, and you would breathe it into your respiratory system, into your lungs. That’s the main mechanism of transfer, which is similar to how previous coronaviruses like SARS and MERS were spread as well. Again, with those, neither one of them showed any signs of foodborne transmission.

Of course, that said, there is always new research coming out. The article I wrote, I based it on all of the current research but there’s always new information. I actually have a call scheduled with a virologist this afternoon specifically to talk about this: they’ve discovered that the virus attaches to these receptors called ACE2 receptors, and some of those are located in epithelial cells higher up in the respiratory system. So, now there’s a theory that maybe it could be more likely that it can be transferable by swallowing or something like that. Although, again, I want to reiterate that thus far in all the cases that we’ve tracked – and that is many – none of them have been shown to be linked to food.

The most convincing thing to me is looking at the studies that have been done in Singapore and in Wuhan, particularly in Singapore where the Ministry of Health there has teams of people that go out and do very extensive interviews with everyone who tests positive for coronavirus. The last time I looked at the data was from a few weeks ago, but at that point they had something like in 90 percent of the cases they knew the transmission route. Ten percent of them were unaccounted for, but 90 percent they know, like, this person got it from this person when they were in a church group together, and then that were at a conference hotel and gave it to these 10 other people. And so they were able to track the spread of the virus. In those 90 percent of cases they were able to account for it, none of them were based on food and every one of them were based on these proximity events where people were in close quarters to each other and breathing in the same air. We can’t rule out that food is a transmission vector because we just don’t know enough, but we can definitely say with confidence that it’s not the prevailing method of transmission. Compared to being close to other people, the risk is relatively low.

FL: Right. So, staying home is still the best advice.

JKLA: Stay home. Stay away from crowds. If you’re going to go shopping, try to go at time when there aren’t a lot of people there. What I recommend actually is to look to smaller markets and grocery stores. First of all, the bigger stores like big supermarkets and big superstores tend to have lines. There’s a lot of people and they aren’t really respecting the proximity rules. Those stores also tend to run out of certain things faster. But, I found that my local grocery stores – for example, there’s a Latin produce market just a block or two from my house, there’s a Japanese market, a Chinese market – yes, they’re smaller but they tend to be better stocked than the bigger stores right now because people don’t tend to go to them. And, of course, a smaller store is better to go to anyway because in every store you’re channeling people through one doorway, right, so whether it’s a big store or a small store you’re still channeling everyone through one doorway. The bigger the store you go into the higher the number of people that have been channeled through that one little area, so the bigger the chances that you’ll be breathing in air that contains some of these virally contaminated droplets. If you go to stores that just have fewer people in them total you’re less likely to pick it up, especially if you go during off-peak hours. Then you’re also supporting your local stores, which is great.

HOW LONG DOES THE VIRUS SURVIVE ON DIFFERENT SURFACES?

FL: Let’s talk about touching stuff. I’ve been washing my hands obsessively, But, I think there was a study in the New England Journal of Medicine a little while ago that has been on a lot of people’s minds. It said that the virus can be detected in the air for a few hours, on cardboard for a 24 hours, and on plastic and stainless stain for 72 hours. I think people heard that and they said, oh, I can’t touch anything anymore. Or to be completely honestly, now it I’m getting packages, I take it into my home, I put it in a room, I close the door, and if it’s not perishable no one touches and I let it sit for 72 hours before opening the package. Maybe that’s overkill but that’s just where my brain went. Do you have thoughts on that study in terms of our grocery shopping? What does that mean? Should I not buy lettuce? I can’t have lettuce sitting out for 72 hours.

JKLA: These are good questions, and they are the kind of questions I had initially. When I started researching and writing this piece, it was for my own sake, both for me and for my family, and for my restaurant. I wanted to know what was safe for ask to ask our employees to do, what’s safe for our customers, what’s safe for my family? And so I had a lot of those specifics question and I posed those type of questions to some food safety experts and virologists. According to all the data that we have right now there are no cases of getting it by touching things and then subsequently touching yourself, but it is theoretically possible for it to happen.

FL: Really?

JKLA: The recommendations to wash your hands and wipe down surfaces, that’s all very sound advice. One thing to understand is there’s a difference between being able to detect a virus and that virus still being transmissible. Just because we can take a swab from a table and say there are viral particles here doesn’t necessarily mean that you then touching that table is going to get you sick. The virus cannot be absorbed through the skin. There’s definitely no problem just touching it. The issues arise when you touch it and then you touch your face, you pick your nose or your rub your eyes or you get it on your lips, and then when you breathe in you might be breathing in some droplets of moisture that have virus on them.

There are a few mitigating factors here. One of them is that every time the virus gets transferred from one thing to another it basically gets diluted. One of the questions I asked about was, if I have an employee in my restaurant who is a carrier but isn’t showing symptoms, and let’s say he coughs once on a cutting board and then he assembles a sandwich on that cutting board and puts that sandwich into a take-out box, and then someone takes it home and eats with their hands, and then that person picks their nose or rubs their eye – what is the likelihood that some of the virus from my employee’s mouth is going to get into someone else’s body and make them sick? Look at that pathway: first the virus gets onto the cutting board, then it has to transfer from the cutting board to a sandwich – which dilutes it – and then the sandwich goes into a box – which again dilutes it – and then you pick it up, it gets on your hands – which dilutes it again – and then it goes onto your face. So, the chances that there is a viable viral load on your fingers, enough to get you sick at that point, are very minimal. And again, it’s not even clear that you can get the COVID-19 disease by just touching your face.

It’s a little bit different talking about viruses versus bacteria. With bacteria, you can start with a small amount of bacteria on your food, and in the right conditions that bacteria is going to multiply so the load of bacteria, the load of pathogens, is going to get bigger and bigger and bigger. With a virus, it’s the opposite. A virus can’t replicate without a host cell, so the amount of virus you sneeze out is the maximum amount it will ever be, and over time that’s going to decrease – no matter what surface it’s on. That includes every time something else touches it and takes some of that virus away or dilutes it. That also includes the natural decay of the virus. Unlike bacteria, you don’t have to worry too much about the virus getting more and more and more; in fact it’s going to get less and less the longer you let it sit there and the more times you handle it.

Now, it does seem really strange – even to me it was hard to believe, how can it be that if someone sneezes on a piece of lettuce and hands it to me and I put it in my mouth, how could I not get sick from that.

FL: Right.

JKLA: I asked that specific question. If I eat a piece of lettuce that a sick person has sneezed on, how can I not get sick? And it depends on the conditions of the air around, like how much of those droplets are still in the air, how close I got to the place where the person sneezed. In the end it’s not really the lettuce that’s going to be the problem, it’s going to be the air around where that person sneezed. Of course, if you take that lettuce and shake it around in the air to get those droplets in the air to where you can inhale them, that’s where it could become an issue. But, given that it’s a respiratory disease, most of the research says that you have to inhale it in order to get it. That’s coming from basically every single public health organization I’ve seen around the world. They all say the same thing, that there are no known cases of foodborne transmission, that it’s a respiratory disease and you get it through droplet transmission.

All of that being said, you know, there are a lot of reasons why you want to be safe about washing your hands and touching surfaces. You definitely don’t want to take a chance that you’re going to get COVID-19 by touching yourself. But, more importantly, there are still all the other pathogens out there like E. coli, salmonella, all those things you can possibly get by not maintaining good food safety protocols in the kitchen, by not washing your hands well. Especially now when the health care system is going to be so overloaded. You don’t want to take any risks – even not related to the virus – that are going to maybe get you to the emergency room or make you have to see a doctor because they are all going to be completely overworked handling this virus as it is. So, as much as you can, whether it’s the virus or anything else, you want to make sure and keep yourself safe and healthy.

FL:  That’s a huge thing. You have to do everything you can to stay healthy right now because going to a doctor is going to be tough and it’s going to put more strain on the system.

BEST PRACTICES FOR SHOPPING AT STORES AND SUPERMARKETS

FL: Okay, Kenji, we’re at the grocery store and we’re shopping. Do you have any thoughts on the check-out line? What’s the best way for us to go about this?

JKLA: I would recommend going to the self check-out lanes as opposed to an in-person cashier. It’s sort of a trade-off because at the self check-out lane you have to touch that touchscreen that a lot of other people have been touching. But the trade-off on balance is that it’s way more important to stay away from people than it is not to touch things. I would say it’s better to stay away from the check-out cashier, first of all for their safety just in case you’re a carrier, but also because they have been coming in contact with and being within breathing room and sneezing room of a lot of people so they could definitely be a carrier as well. As much as you can I would try to avoid getting into close proximity of other people.

The other thing I would recommend is that you don’t have to obsessively use hand sanitizer. Like at home, soap and water is just as effective as destroying the virus as hand sanitizer is because it’s a lipid covered thing, it has a lipid shell that gets broken down by soap. But, when you’re out in public it’s not really practical to wash your hands with soap and water, so I would suggest taking a little bottle of hand sanitizer with you when you go to the supermarket. Before you get back into your car or before you touch your car door or grab your steering wheel, sanitize your hands of anything you might’ve picked up while touching those screens or bags.

Also, try to avoid using cash. Even avoid credit cards if you can. If you can go touch-free, do that. Pretty much everyone’s phone these days has a touch-free payment option and most larger cities have that option. So, as much as you can go touch-free with everything.

Same when you’re picking up food at a restaurant. What we do for instance is, we have a table set up at the front. You place your order and pay for it online, and we tell you what time it’s going to be ready. We put it on the table, you use the ADA handicap button to open the door, walk in, pick up your food, and walk out. No contact with other people, that’s really the most important thing we could all be doing right now.

ARE THERE ANY MAJOR FOOD SUPPLY CONCERNS?

FL: A lot of people have been joking about and/or experiencing and being horrified about toilet paper shortages and going to the store to find the shelves emptied. I’ve been reading reports that say the U.S. food supply is fine, there’s not an issue that we’re going to run out of food, that’s not something we need to be concerned with, and we shouldn’t be hoarding. Have you stockpiled anything? If not, why are you confident that we don’t need to?

JKLA: At my house we actually have an earthquake emergency kit. We’ve stockpiled stuff just in case there’s a big earthquake here in California. We have supplies for the three of us to last a couple of months already, so we didn’t too much stockpiling on top of that. I have three weeks to a month worth of food, which is what I recommend. There’s no reason to go out and buy three months of food. You’re going to get bored of eating if there’s no fresh produce.

When you go to the supermarket, and especially if you went a couple of weeks ago, it might seem like there’s a big food supply issue, but it’s all temporary because of hoarding behavior. According to all of the information that’s out there, there shouldn’t be any issue with food supply. We’re still going to be growing food. The couple of places where there might be an issue is harvesting, especially with migrant workers who tend to live in cramped conditions and move around a lot, which are both things that are not good when there a pandemic. How we’re going to deal with that might be an issue coming up in the future that we’re not exactly sure how we’re going to tackle.

The other is how it’s going to affect the trucking industry. All indications are that we’re not going to have food shortages. We might just have to figure out how to get them where they need to be. And also, obviously, less people are eating in restaurants and more people are going to supermarkets now, so shipping companies have to figure out the logistics of changing those routes and altering their delivery patterns. Everyone is working hard to make sure their own businesses and livelihoods don’t fail during this, so you can be guaranteed that everyone on the food supply side is going to be working as hard as they can to continue producing the food.

ARE IMPORTED FOODS SAFE?

FL: Another question about the food supply chain is about imported food. Because we first started hearing about this disease in other countries, some people are nervous and asking, should we be buying food from those countries? To your point before, the virus evaporates and breaks down when it’s on a material. Yes, food is being shipped over a long distance, but is there any kind of indication that we should be worry about imports from those countries that were first impacted by the virus?

JKLA: Again, there’s no indication that there’s been any transmission via food or packaging. Like you said, the virus lives on hard surfaces the longest; so far what we’ve seen it’s about three days. Most goods coming in from other countries spend much longer in transit than three days, so the chances that there’s something from, say, China on a bottle of soy sauce that you buy, a viral load that’s going to make it into your supermarket, the chances are practically zero. There’s a much higher chance that the person stocking the supermarket shelf is likely to contaminate it than a person at the point of origin. The answer is no; you don’t have to avoid imported foods at all.

Chinese-Americans are Americans; you don’t have to avoid your neighbor because of their ethnicity any more than you would anyone else right now when we should all be avoiding each other. But, it’s still fine to take out food from the Chinese restaurant, just as it’s still fine to order a pizza or order whatever you want. If you trusted the restaurant before to maintain proper hygiene standards then you can trust them now. With restaurant workers, there are very strict hygiene rules and protocols that are followed – everything from the placement of the sink to how often people wash their hands to keeping logs of temperatures. All of those things are designed to keep you safe. The chances of food getting contaminated at a restaurant are probably lower than it getting contaminated in your own home; people in restaurants are probably cleaner about how they cook than you are at home.

That said, when you’re getting something from a take-out box and you don’t know exactly what happened to it on the way to your door, it’s very understandable that people are nervous about those things. I wouldn’t judge anyone for wanting to cook their own food all the time, but certainly you don’t have to avoid products that were made in China, Italy or anywhere else.

TAKE EXTRA PRECAUTIONS WITH TAKE-OUT OR DELIVERED FOOD

FL: If we do get carry-out or we do get delivery right now, it sounds like most of the advice is you’re probably going to be fine, but if we want to be extra safe do we go home and reheat it? Is there a kill step that you want to do at home? Do you eat it off of a plate instead of out of the box?

JKLA: You certainly want to be extra careful in these times. With pathogens, virus and bacteria, making food safe to eat is a function of temperature and time. The higher the temperature you cook it to the less time it has to spend at that temperature to bring the bacterial or viral load down to a safe level. Those temperature and time graphs like different for each pathogen, but they all fall within the same range. What we do know is that for the current coronavirus three minutes at a 149 degrees Fahrenheit – that’s a little bit less than 65 degrees Celsius – three minutes at or above that temperature is enough to basically sterilize it. It’s a 5-log reduction, so for every hundred-thousand viral particles in there you’re left with one after three minutes at 149 degrees or higher. If you want to be extra safe, you can reheat your food at home. Stick with food that can be reheated. Use a thermometer to check that the internal and external temperatures reach 149 degrees and stayed there or higher for at least three minutes before you eat it.

As for the packaging, I would definitely recommend that if you get take-out containers, transfer the food to a plate, toss out the take-out containers, wash your hands carefully before you sit down and start eating dinner. Make sure those take-out containers don’t touch the table where you’re going to be eating, or if it does wipe it down really well. Similarly, if you’re going to buy groceries, with fresh produce there’s only so much you can do, you can wash it. Some people recommend washing it with soap; they do make special vegetable soaps that can be effective. Basically, anything that will cut grease will also destroy a virus. If you’re buying dry goods, things that come in watertight cans and bottles, you can wash those the same way you would wash your hands. And things that come in bags, like flour or sugar, transfer those into a clean container, throw out the bag it came in, wash your hands carefully before you use or before you put it away.

FL: You don’t have to be paranoid about it. Be safe and take the extra precautions, but don’t live in abject terror.

JKLA: Don’t live in abject terror. Everybody has their own level of risk assessment. You want to make sure that whatever your level of risk assessment is that you don’t put other people at risk. Be careful about how you expose yourself to other people. In your own home you’re making decisions for yourself and you have to be willing to decide what you should be going through. But, you should know the information out there and you definitely shouldn’t panic because stress and lack of sleep are things that concretely compromise your immune system. The more stressed out you are the more likely you are to get sick, not necessarily from coronavirus, but sick from anything. You want to try to relax right now. Get good sleep. Make sure you’re in a good state of mind or as good a state of mind as can be. It’s important for everyone.

HOW ACCURATE ARE EXPIRATION DATES?

FL: Some of us are stuck at home now and we’re getting reacquainted with the nether regions of our pantry and the very back of our fridge and freezer. I laid eyes on a bottle of ketchup my friend had that was brown inside the bottle and the expiration date was 2003. We threw that out. I’m not that desperate for ketchup! But, I think we all know that with expiration dates on packaged goods, often you can eat them after that expiration date. Do you have guidelines for how long or how old is too old?

JKLA: It’s difficult to say how old is too old. Expiration dates are always just an estimate because there’s no way the manufacturer is going to know exactly how it’s being stored, how it’s being shipped, and all of those things can factor into the expiration dates. I would say for the things that people are most concerned about – things like eggs and milk – honestly the sniff test is a pretty good way to tell. Your milk is going to be fine until it’s not. For eggs, it depends on the state, but generally the expiration date on the carton is 30 days after the day it was packed, and eggs are typically good at least 60 days after they were packed. If you’re a little worried about them, crack them into a separate bowl before you eat them or add them to a recipe. As for canned goods, usually the expiration date is fine to ignore as long as the can is not bulging, the can is not cracked, there’s no sign of bacterial activity going on inside it. If it’s five years old, maybe throw it out. But, if it’s off by a few months or even a year, I would say in the vast majority of cases it’s probably fine. With jarred goods, check the button on top and make sure they are still sealed because that’s a good indication of any activity going on inside, any gasses being producer or anything like that.

And, of course, as with anything, again I want to stress that you’re the one who ultimately decides your own risk factor, so don’t do anything that’s going to get you in the hospital. If you’re at home and you’re quarantining the way you should, you’re not doing anything dangerous, you’re remaining stress-free, you’re probably going to be fine.

VET YOUR INFORMATION SOURCES. STAY UP TO DATE WITH RESEARCH AND RECOMMENDATIONS

FL: I know this is a caveat you would add: information is always changing. New information that comes out might end up contradicting what we’ve talked about here today. Just keep being safe, wash your hands, don’t be reckless, avoid other people, stay at home, keep your family safe.

JKLA: I would also add that whenever you hear a bit of information or a bit of advice check the sources, make sure that whatever you’re reading is backed up by actual scientific study or by some recognized public health organization. Because there is a ton of fake news going around about this and it’s especially dangerous right now because bad information can either cause a panic or it can potentially get a lot of people sick. Be diligent about checking the sources of whatever channel you get your news from; make sure that news is being backed up by proper scientific research and public health organizations.

There’s always new information coming out. We are planning on keeping that article up to date as possible. If anything changes at all we have no problem saying, hey, we were wrong. We hope we’re not wrong about anything, but I’m going to be constantly keeping in touch with virologists and food safety experts to make sure whatever advice we’re giving in that article is the most up to date with current recommendations and scientific consensus.

J. Kenji López-Alt is the Chief Culinary Advisor of Serious Eats, Chef/Partner at Wursthall (a San Mateo beer hall), a New York Times food columnist, and the author of The Food Lab: Better Home Cooking Through Science. His upcoming second book is an illustrated children's book. Every Night is Pizza Night will be released on September 1st. Currently, Kenji is donating 100% of his sales commissions from books purchased or pre-ordered through his bookshop.org page. He is also raising money to provide free meals to frontline workers and those in need in the San Francisco Bay Area. Ongoing monthly donations can be made through his Patreon page, where 100 percent of donations will go directly to producing and distributing free meals.