Special Sauce: Kenji on His Food Safety Article

It’s obviously still not business as usual at Serious Eats (or anywhere else in the world, for that matter), so we’re going to continue to produce Special Sauce episodes that deal with the coronavirus pandemic. On this week’s episode, we once again hear from Serious Eats’s Chief Culinary Advisor Kenji López-Alt. Kenji has been pitching in mightily on so many coronavirus-fighting efforts, both on Serious Eats and off.

On Serious Eats, he published an epic post on coronavirus and food safety that millions of people have found useful. We followed that with our first Special Sauce episode focused on the impact of coronavirus, which detailed what’s happened at Kenji’s restaurant Wursthall since the pandemic broke out. Then we released a video featuring Kenji in which he answered many of the questions he posed in the original post. To complete this multimedia effort, this week’s Special Sauce episode features the audio track from the aforementioned video, since we think the information is that important.

Here are some examples of the kinds of questions answered in this episode: Can I be infected by coronavirus by touching or eating food? Is it safe to eat raw foods? What is the safest way to shop at the supermarket? Is it okay to buy produce from open bins?

And as Kenji and I both note in this episode, he has promised to continually update the original post as new information becomes available in this rapidly-changing situation.

On a personal note, Kenji has really helped so many people in these exceedingly tough times by answering these questions. The least we can do is ask that you return the favor, if you’re able. If you can afford to support Kenji’s Wursthall-centric coronavirus initiative by donating to his Patreon account, or by directly purchasing meals-for-free from Wursthall’s own take-out website, please do so.  


Ed Levine: Hi, I’m Ed Levine, founder of Serious Eats with another Special Sauce coronavirus update. Normally we rely on our chief culinary consultant, Kenji Lopez-Alt, author of The Food Lab, for his recipes and the science behind them. But these times are not normal. These days Kenji has been using his rigorous research skills, he did after all graduate from MIT, to gather best advice about how to stay safe from the coronavirus when it comes to the food we eat, shop for, cook, and order in. He published his findings on Serious Eats last week and millions of people around the world found it useful. This episode of Special Sauce runs about 15 minutes as Kenji answers some of the most fundamental questions he posed on that Serious Eats post.

Kenji Lopez-Alt: Hi, this is Kenji Lopez-Alt and I’m here at my restaurant Wursthall. Like many restaurants and many businesses, we are largely closed right now. We’re open for takeout business only, contact free takeout. When this transition was happening and even before that, I was very much concerned as everyone is about the safety of my employees, about how this virus spreads, about the best ways to keep people safe, including my family. I have a young daughter, I have two senior parents. So I really wanted to get the best information out there. So to that end I did a whole lot of research in scientific journals, scientific papers, newspapers, recommendations from health organizations around the world as well as extensive conversations with an epidemiologist, a virologist, and a food safety expert. That said, what are the most important things I could be doing to stay safe?

Social distancing is by far the most important thing you should be doing right now. This is a respiratory virus, which means that it’s transmitted by droplets or aerosolized spit and mucus that carries a viral load and that can hang out in the air for several hours in fact. So the best way to ensure that you don’t pick up the virus is by not coming into proximity with anyone else. The next most important thing you should be doing is just practicing good general hygiene. So keeping your house clean, keeping surfaces clean, washing your hands frequently with soap. Importantly, not touching your face or touching your face as little as possible. If you have to scratch your face, rub your eyes, something like that, make sure you wash your hands carefully with soap before you do that, because you don’t want to accidentally pick up a viral load from some surface and then get it into your nose or your mouth or your eyes.

Does my face have any specific hot zones? So when I say hot zones, I mean places that you’re more likely to get the virus into your system if you touch it. The answer’s yes. The main place you want to avoid touching is your nose. So stop picking your nose. Following after that, your eyes and your mouth. The chances that you’re going to get it from your eyes and the mouth are much lower, although recently there have been reports of conjunctivitis related to the coronavirus. So it is quite possible that you can get an infection through your eyes. But the nose is the one that we know is the main place to avoid. But again, you should be avoiding touching your face at all as much as you can and certainly washing your hands before you touch your face.

How does the coronavirus gets spread? Well, it’s a respiratory virus, so the primary way in which it gets spread is by a droplet infection. So you breathing out or coughing or sneezing, putting moist droplets that are loaded with the virus into the air and then someone else coming by and inhaling those, and that’s why everybody has been recommending social distancing so that you don’t breathe in other people’s air.

Are there any other ways that it could be spread? There are a couple other theorized ways that it could potentially be spread. One of them is through contact, fomite transmission. So if somebody, say, sneezes onto a table and then you touch that table, you pick up some of the virus on your hand and then you touch your face, you touch your nose or your eyes or your mouth. It’s possible that you could then get infected through that method, although it is much less likely that you’re going to be infected that way than just direct droplet inhalation.

Another possible route is fecal oral or fecal respiratory, so that’s when the infected feces of a human. So far, we’ve found that about 50% of people have viral RNA in their stool, then we’ve produced viable virus out of that. So it is possible that a restaurant worker with very poor hygiene or someone in your home that didn’t wash their hands could potentially spread some amount of fecal matter onto food or onto your hands and that you could then ingest it and even if you do ingest a little bit of it, it’s probably not going to get you get you sick. At least not from coronavirus.

Can I get the coronavirus by touching or eating food? So far there have been no known cases of foodborne transmission or food packaging related transmission. That is not to say that it’s completely out of the question. There is definitely the chance that you could get it, but thus far there have been no known cases and according to all of the experts I spoke to, the chances of getting it from eating food or handling food or food packaging are extremely slim, especially if you practice good hygiene while you’re preparing and eating your food.

Is it safe to eat raw foods? This was a question that I specifically asked a number of experts on whether it was safe to eat, say, salads or fish, sushi or anything that you would normally eat raw. Is it less safe to eat that now? The answers I got were it’s probably just as safe now to eat those raw foods as it was before. Even if a worker were to, say, sneeze right in your salad bowl, toss it, put it on your plate and hand it to you, the chances that you are going to get infected from that salad are very, very slim. As we know, it’s a respiratory virus. So unless you’re taking that lettuce, shaking it around in the air, getting droplets in the air and then inhaling those, the chances that you’re actually going to get it from eating that lettuce are slim. Your mouth contains proteolytic enzymes, your saliva claims contains proteolytic enzymes, which break down proteins indiscriminately, and that includes the membrane around the coronavirus.

Your gastrointestinal system is also a different system from your respiratory system. You share a little bit of the same tube in the back of your throat, but if you’re swallowing and you’re actively eating, the chance that a viral load gets deposited there and that that load is enough to then subsequently get you infected, I am told is very, very slim. So you’re probably safe even eating raw foods.

How long does the coronavirus last on various surfaces? The coronavirus can last for three days or so on plastic and steel, about 24 hours on more porous surfaces like cardboard, four hours on copper and in the air in aerosolized form, we know that it can last a minimum of three hours. We don’t really know exactly how long it can last, but projecting the graph, it looks like it’s probably about six to eight hours or so. In aerosolized form.

Does heating destroy the virus? The short answer is yes. Heating does destroy the virus. So if you’re still nervous about eating raw foods, and that’s totally understandable, a sure-fire way to make sure that the food you’re about to put in your mouth is virus free is by cooking it and heating it. What we do know is that 149 degrees Fahrenheit, which is about 65 degrees Celsius, at that temperature and higher it takes about three minutes to completely make sure that the food is going to be virus free. So if you’re heating up liquid foods like soup, make sure that they come to a simmer. Let them simmer for three minutes and it’ll be safe. If you’re heating up solid foods, use a thermometer and make sure that it comes up to 149 degrees Fahrenheit or higher and that it maintains that temperature for three minutes before you eat it and that’s a pretty good guarantee that it’s going to be virus free.

What is the safest way to shop at the supermarket? Well, supermarkets can be a little bit dangerous because they tend to be crowded and because lots of people pass through them, especially larger supermarkets. So when you go to a supermarket, you as much as possible want to avoid getting in people’s space, getting in spaces that were recently occupied by other people. What that means is I would recommend using the self checkout lane instead of going to a physical cashier, a real person, because the virus again is primarily spread through person to person, droplet infection, not through touching things. So even if a lot of people have touched that touchscreen, the chances that you’re going to pick up the virus or get sick from touching that touchscreen are very, very slim especially if you wash your hands carefully before you bring them near your face.

So I would recommend using the self checkout lane if possible, using cash free payment systems or cardless payment systems are even better. So everyone’s phone these days probably has a touch-free option. If not, you can use a credit card, just wash your hands well and try to avoid cash if you can. If you’re forced to, again just make sure you wash your hands well before you touch your face. The other thing that I would recommend is checking out smaller local markets as opposed to the big supermarkets because basically the more number of people that pass through a space, the higher the odds that an infected person will have passed through that space and left a viral load somewhere in it. So the fewer the people that pass through the doorway of the supermarket, the better.

So I like to shop in smaller local shops and I’ve found actually that the selection at those shops tends to be better these days than the large supermarkets where a lot of these people who are hoarding food go shopping. And of course you’re also going to be helping your local community and small businesses are really hurting right now, so they will definitely appreciate your business.

Is it safer to use paper, plastic or your own shopping bags? The truth is, every expert I talked about this has said they’re all just about the same level of safety, which is very safe. Plastic bags and paper bags are made in factories and they’re shipped to supermarkets. They take a long time before they’re actually used and we know that the virus only lasts about three days on plastic surfaces, one day on paper surfaces. So chances are that amount of time has… You’re not getting farm fresh plastic or paper bags. So the virus is not going to be on those bags when they get to the store. So the only real way that you could possibly get infected by them as if, say, the person bagging your groceries blows into the bag or sneezes near the bags. As far as using your own bags go, using a cloth bag is actually safer than using a plastic bag. A little bit safer, both of them are pretty safe. Cloth is a little bit safer only because you can wash it in the washing machine and detergents and soaps are actually very good at destroying this virus.

Should I be using hand sanitizer? Well, the good news is you don’t really have to go crazy with the hand sanitizer, especially if you’re at home. Soap is going to be just as effective. Soap is designed to break down fats, lipids and this is a lipid coated membrane. There is a lipid membrane around this virus, so that gets broken down very easily by soap. So soap is the best way to wash your hands at home. Use cool water just because hot water, if you repeatedly wash your hands with hot water, it’s going to lead to more dry hands and more irritated skin. So you’re going to find that it’s easier to use cool water if you’re frequently washing your hands.

The time I would recommend getting at least a small bottle of sanitizer or maybe getting some sanitizing wipes is for when you go out. So say you go to the supermarket, you go to another store, you’re coming back, you’ve touched some things, before you touch your car door handle or before you touch your front door knob, just give yourself a good wipe with the sanitizer to make sure that you’re not depositing any virus onto those surfaces that other people might subsequently be touching.

Is it okay to buy produce from open bins? Yes, it is okay to buy produce from open bins even if other people are touching it. So a virus requires a host cell in order to replicate itself. So once the virus leaves a host body, say in the form of a sneeze or a cough, it’s not going to grow in numbers the way, say, bacteria could or fungus could. Once it comes out of your body, that’s the most virus that’s ever going to be in that load and from there it’s going to steadily decrease. It’s also going to go through a bunch of dilution events. So if it’s on say an apple and you have a certain amount of viral load on that apple and then a bunch of people touch that apple, well every person has gotten a little bit of virus on their hand, which means that there is now a little bit less virus on that apple and it’s now spread out over more surfaces, it’s going to break down faster, and all those people are probably going to wash their hands, hopefully.

So really the odds of contracting the virus just by touching raw produce, even produce that other people have touched, are very, very slim. Especially if you practice good hygiene, wash your fruits and vegetables when you get them home, wash your hands before you touch your face or before you prepare and cook food, you should be safe.

Is it safer to order take out, delivery or to shop at the supermarket? All three methods are actually relatively safe. Again, the thing you want to really look out for is proximity to other people, so at the supermarket go during off peak hours and avoid other people. If you’re going to get take out, try and order from a restaurant that offers contact free take out, that is where they would leave the food on a table, step back, allow you to come forward and pick it up and if you’re going to get delivery, the same thing. Ask the delivery driver to leave it on your doorstep, step away, then you go and pick up the food and bring it into your house. You want to avoid proximity to other people as much as possible.

Can I get it from eating Chinese food or imported goods from other countries? The answer is you’re not any more likely to get it from Chinese goods or imported goods than you are from anything at the supermarket or at any other restaurant. The disease did originate in China, but it spread person to person, which is why health organizations and governments have been limiting the movement of people but not the movement of goods. We don’t really know of any cases where it’s been transferred via goods, especially imported goods like food that are going to be in shipment for at least days, weeks, sometimes even months. In that amount of time, there’s not going to be any virus left by the time it gets to its point of destination. So with imported goods, it’s more likely to be infected by the person stocking the supermarket shelf, more the person unloading the truck than it is at its point of origin. So the answer is no. There is no higher risk associated with imported food or Chinese restaurants or any other type of restaurant.

So in summary, I want to reiterate that this is a novel virus. So there’s a lot we don’t know about it. That said, we do know that it’s spread primarily through droplet inhalation and we also know that thus far there have been no known cases of food related transmission and that’s the agreement of every health organization around the world and every expert that I’ve spoken to. So while it is theoretically possible that you can get it through eating food or through handling food, the odds of that at this point are quite slim. So you can feel good about cooking at home or even ordering takeout from restaurants.

So what can you do to help? The best way to help is to keep yourself healthy and to keep your community healthy, and that means social distancing. So keep yourself at home as much as you can. If you do need to go out, avoid crowds, avoid other people, do all your shopping in three to four work batches… Sorry, three to four week batches so that you don’t have to frequently go to the supermarket and just stay healthy, clean and safe. And that’s good protection for you and for your community.

If you want to help beyond that, I would really suggest looking towards local organizations that are helping with coronavirus relief. I know that in my community in the Bay area, there’s a number of organizations that have sprung up since the outbreak started. In fact, my own restaurant, we are providing free meals to first responders, firemen, emergency room workers, as well as people in the community who need food because they’re out of work or because their children are out of school. There are lots of people doing good work out there. I urge you to look into that. See how you can help. If nobody’s doing anything around you, start your own initiative if you can. We’re all just doing the best we can right here, right now and I hope that you stay safe and I hope that you keep eating good food.

Ed Levine: Kenji Lopez-Alt is Serious Eats chief culinary consultant and author of The Food Lab, Better Home Cooking Through Science. He spoke from Wursthall, his restaurant and beer house in San Mateo, California. We should note that scientists are learning new things every day about this subject. So as Kenji gathers new information about food safety and the coronavirus, he will be sharing that info with us.