Home fermentation and how safe that is.

I had a question about knives. 

Do you ever use a serrated knife?

If not, why don't you? I use them more often than not, especially to cut thick skin or slippery vegetables. I find it easier to cut through the skin of a tomato with a serrated knife. Am I doing something bad in doing them? I've started using a chef's knife more just because I've seen you do it. And I think, "Oh, maybe this is a thing that I should be doing." Adam: I'm pretty sure the main reason normal people reach for serrated knives in the kitchen is because serrated edges work even when they aren't very sharp. This is unlike a straight edge knife, a chef knife, which is pretty much useless in the kitchen unless it has been recently sharpened. Less experienced cooks are less comfortable sharpening knives. So they reach for serrated knives, which work even when they are pretty dull. Furthermore, it's less expensive to manufacture a decent serrated knife.

So more people can have them as opposed to a decent chef's knife, which is more expensive. The serrated knife is cheaper. Pick up a serrated knife and pick up a chef knife and you will probably notice the serrated knife is lighter. The most expensive part of making a knife is sourcing the steel itself. I know this from having commissioned the manufacturing of my custom chef knife. The steel is where the money is, especially in the contemporary era of computer automated manufacturing, automatic forging, all of that kind of thing. The labor costs of making a pretty good knife are surprisingly low now. It's really all about materials.

It's all about that steel. Compared to a chef knife, you can make a good serrated knife with less steel because the serrations themselves make the blade more rigid. The little saw teeth at the end of the knife resist force from multiple angles. I believe this is the physics concept known as moments of inertia. A serrated knife has more moments of inertia. It's why an arch is stronger than a flat beam. It's why a folded paper airplane is more rigid than a flat sheet of paper. The irregular shape distributes an external force in a multitude of different directions, whereas a regular shape concentrates that force in one direction and the blade bends or breaks if it's too thin.

Pretty sure that's how that works? So especially with modern manufacturing methods for actually cutting or molding the little teeth, it's just less expensive to make a serrated knife because you need less steel to make a knife that won't bend or break easily. So more people have access to serrated knives that actually cut. And they cut even when they are pretty dull because of the teeth.

The teeth in a serrated blade concentrates

The force of your cutting onto a few teeny tiny little spots on the food.

And even if you can't slice through the food, you can tear through it. That said, if you've ever encountered a serrated blade that was also very sharp, you know how terrifying that is. Like when we bought our first house, my dad gave me this little like pistol grip hand saw that came with its own little holster. And I thought, "This is ridiculous.

This is just for gardening dads who want to play army when they go out to prune the hedge. I was about to throw the holster out when my skin just barely grazed one of the teeth on this brand new, very well made saw, and the cut was brutal. I swear I can cut myself just by looking at that damn saw. It is nuts. A blade that is both serrated and sharp is a straight up killer. See hunting knives. But you rarely encounter serrated blades that are also very sharp because as you use them, you will dull the edges. And it's much harder to sharpen a serrated blade than a straight blade.

There are methods. It depends on the kind of serrated you have, tooth serrations versus fan serrations. For example, fan serrations are the ones that look like little scalloped edges, like somebody kind of scooped metal out of the edge of the knife. Those are pretty common in kitchen knives. One thing that I've seen people do with fan serrations is they take a honing steel, that long metal cylinder on a handle that comes with like every knife set. You take the honing steel and you set it into one of those individual little scoops on the knife edge. And one by one, you drag the knife across the honing steel, thus sharpening that one little serration. Then you set the steel in the next serration and you proceed.

The professionals have better tools, I imagine, but I'm sure at some point you just have to completely flatten the edge and start fresh with totally new serrations, which I doubt many people do anymore because you can make a new, good serrated knife for not that much money. Are you doing something wrong, Kim, by cutting your tomato with a serrated knife? Well, that's a matter between you and your tomato, Kim. And I wouldn't dream of invading the sanctity of that relationship. I will tell you that you're not alone. Lots of people use serrated knives for tomatoes precisely for the reason you gave, which is to get past the skin. Tomatoes are soft and easy to cut, but their skins are not. Not only are their skins tough, they're also very smooth, which means there's fewer imperfections for your knife to grab onto which means a dull knife could actually slide right off the tomato skin and you could cut yourself. The problem with serrated knives is that they don't really slice food, they tear food.

They tend to produce rough raggedy edges on food, by their very nature, right? They work by concentrating force onto a few small points instead of evenly across an entire edge. That's why they're so effective. They tend to produce raggedy edges on food that just don't look very nice. And more importantly, those serrated knives do more cellular damage at the surface of the cut. And this unleashes enzymatic reactions and oxidative reactions that results in the cut surface turning brown faster or going soft and gummy faster, or maybe drying out faster in some cases.

It's obviously a huge deal when cutting

Onions, right? cut onions with a serrated knife and you will send riot control gases spurting every which way and your eyes will suffer.

I cannot remember the last time I

Cried cutting onions because i have a sharp chef's knife.

And that's also why I almost never use a serrated knife.

I just don't need to. I am lucky enough to have a good chef's knife. I am comfortable sharpening it, and it's pretty good at doing almost everything that I could need any knife for in the kitchen. And I make an effort to favor my chef's knife, because I want to show people that all they really need is one decent knife. A mid-price chef knife, something around 50 bucks these days that can get you farther than a whole $50 set of cheap knives. I use my chef knife because it's easy to sharpen and I keep it sharp. And I suspect it might even be more versatile for me than a knife sharpened by like a real chef or someone who sharpens knives for real chefs, because I don't use real chef sharpening methods. I do not use wet stones.

I use simple consumer grade pull through sharpeners, which don't produce as fine of an edge. The edge comes out a little rough, has little microserrations on it. And so it bites just fine through a tomato skin. It does basically all the jobs that a serrated knife could do, except for cutting bread. I have a bread knife. I use it for bread, and that's basically it. Professional sharpeners who use wet stones, they have their own techniques for giving the blade a little bite, as they say, if they want to, if that's what the chef wants. Chefs who do elite level knife work like sushi chefs, they have blades in their collection that have been sharpened to have a little bit of bite.

I imagine they use those for some vegetables. And they have other knives in their kit that are just straight razor blades, like you could only see imperfections in the edge with a very powerful microscope. And those knives, they use for cutting fish. That's how they get those glossy smooth cut edges on fish for sushi. I don't do anything so refined in my kitchen. I just have a mid-priced chef knife. Quality piece of German steel, nothing more. And I run it through a pull through sharpener once every couple of weeks whenever I notice it going a little dull.

Get a pull through sharpener that is multi-stage, meaning it's got like one little alley for roughly stripping away metal and then it's got one or more additional little alleys for progressively refining the edge. And get one that is made for the basic angle your knife is made to hold and the basic kind of steel that you have. Some knives, particularly Japanese or Japanese style knives, are made from harder, more brittle steel that could crack or break in a sharpening surface that's designed for slightly softer European style steel. A good pull through sharpener will say on the package what kind of knife it's made for, what kind of steel it's made for. And a good mid-priced chef knife will tell you what kind of steel it's made out of. If you don't have the box anymore that you bought the knife in, you could maybe look it up on the internet if you remember where you got it. Find out what brand it is. You could probably look up the model and find out what kind of steel it is.

But this is why when I designed my custom chef knife, I had them laser engrave the type of steel into the side of the knife so that you'll always know.

By the way, we are on track

To sell more of those in time for christmas.

I will keep you in the loop on that. Side note, it remains absolutely astounding to me that chefs and other knife nerds really expect you and me to sharpen with wet stones. I've advocated consumer-grade pull through sharpen errors, I have gotten all these knife nerds in the comments saying, "Oh, you're going to ruin a lot of people's knives.".

Watch how messy and physically taxing it is to sharpen with a stone and how much you need to know and practice in order to do it well.  It is absurd to think that real people with real stuff to do in their lives are going to sharpen their knives that way. It is pure elitism. Pull through sharpeners have come a long way. There's some very good ones on the market now. Get a well reviewed multi-stage pull through sharpener that's basically matched to the kind of knife that you have.

Remember to actually use the sharpener. Do that, and cutting in the kitchen suddenly becomes so much easier. A sharpener like that will not make the cleanest edge, but as we just discussed, I actually think that's kind of good. Little micro imperfections, microserrations are good. It means you don't need a serrated knife. It won't make the longest lasting edge so you'll need to sharpen pretty frequently, but that's fine because it only takes a second to do it with a pull through sharpener and it doesn't make a big mess. Sharpening frequently definitely shortens the life of the knife because sharpening is all about removing metal. And pull through sharpeners probably remove more metal in a single sharpening than a.

Davis Wells does when he's using his stones. But if you're taking knife advice from me, then you probably don't own a $10,000 hand forged chef's knife that you want to last for generations. Have pretentious chefs started naming their knives the way that pretentious warriors used to name their swords? "Hey chef, can you slice up this roast?" "No problem. Squire, fetch me Excowibur.". Cowibur, because he's slicing beef with it. And it's an ex-cow because it's dead. And knife edges have burs. Anyway, right here is one of the reasons why cooking has become so insufferable.

Cooking has been invaded by people, mostly men, who wish they had a war to fight. But the world is generally more peaceful and the wars we do fight are increasingly fought like fricking video games with drones and stuff and there are fewer opportunities for dudes to demonstrate their individual valor in combat. And lots of dudes just seem to need that, so they go to work in kitchens instead because cooking, I imagine, can kind of feel a little bit like combat.

You're using very dangerous destructive tools.

You're cutting flesh with them.

You're working under very intense time pressure and you have to work very closely with others in your unit. The leadership structure is very hierarchical, and that's good for people who have daddy issues, which people who work in kitchens often do and people who join the military often do. Dudes need to be off fighting a war but there is none, so they go to work in the kitchen and they make life hell for everyone because war is hell.

The weekend warriors who only cook at home can be just as bad. Dear Lord, find something more important to do with all of that energy, boys. Prove your valor elsewhere. Let the rest of us just get dinner on the table. Anyway, I don't care that my sharpener removes a lot of metal because I don't have a crazy expensive knife, because I think my things should serve me and not the other way around. My chef knife works great for me. But if you want to use your serrated knife, Kim, don't let the kitchen warriors intimidate you into using something else just because they say that your knife isn't field grade. I wouldn't want to work with people who'd clearly rather be in battle, but that's just me.

This is Guadalupe from Buenos Aires. I was wondering exactly how dangerous is it to prepare fermented things at home such as kimchi or sauerkraut. I've always found contradicted information like, "Yeah, it's really not likely that you'll get botulism or another thing like that from making your own sauerkraut, but then you might.". That home always gives me second thoughts on trying.

What's the science on that? Adam: Okay.

Hold that thought, Guadalupe. We have a related question. I'm going to group you two together. Jade: Hey Adam, my name is Jade. I'm from Colorado and I have a question about fermentation because I think it's one of the best things that can happen to food. So me and my mom both do this thing where we'll get a food product that has some sort of live culture in it, and then use a piece of that to extend it. Like my mom will get live culture yogurt, and then added to some cream to make more yogurt. Or I will get a bottle of Kombucha with live culture and put it into another bottle with some water and some tea and make more kombucha.

My question is, is this a good idea health wise? is there anything that I should, to your knowledge, be worried about? Thanks. Adam: So Jade and Guadalupe, you will be excited to know that I do have a article about lacto-fermentation in the works. I have some sauerkraut going in the basement right now and I got some dill pickles going, on which I have been doing a time lapse shot for like a month now. I am extremely excited to crack open that camera and see if it worked. If you don't see a time lapse shot of dill pickles fermenting, you will know that it did not work. I will weep if that happens. When we bought this house, a selling point to me, it was all of the small closets in the basement. I've got this one that's underneath the stairs like where Harry Potter would sleep.

It's totally isolated. No light gets in there, no vibrations. Nobody ever thinks to look in there. I ran power in there and now I can set up month long time lapse shots and it is so much fun and terrifying because you don't know if they actually worked until the end. You can't touch the camera to check the progress because you'll move it slightly and that'll mess up the shot. Anyway, I'll go into much more detail  about what lacto-fermentation is, but here is the short version for those who don't know. Lacto-fermentation is the kind of fermentation that gets you dill pickles and sauerkraut and kimchi and fermented chutney and yogurt and cheese obviously, though that's kind of a different process, and kombucha, though there's more going on in kombucha than just lacto-fermentation. That's probably part of it though.

Lacto-fermenting pickles involves taking some vegetables usually and adding enough salt so that the only bacteria likely to be able to thrive will be the various kinds of lactic acid producing bacteria. Not just lactobacilli, but there are many others. These are bacteria that are generally benign to humans and often quite beneficial to humans. They make up a lot of our microbiome, all the microorganisms that live inside us, mainly in our intestines that play various important roles in our digestion and overall health. There are exceptions to that whole benignity thing. They're not all benign. One genus of lactic acid producing bacteria is Streptococcus. And if you've ever had strep throat or pink eye or meningitis, then you have met some of the less benign species of lactic acid producing bacteria.

But that's not really relevant to the present discussion.

It's just a fun fact.

There doesn't seem to be any known

Case of someone getting strep throat from pickles.

I can't believe I just Googled that, but I did. Lactic acid bacteria are also significantly responsible for tooth decay. That's not great. But generally they're good bugs and they can handle a salt concentration of 2 to 2.5% by weight, which is the classic lacto-fermenting range. Other less friendly bacteria can survive in the presence of that much salt, but they'll be less happy.

And the lactic acid bacteria will outcompete the other bacteria and they'll be able to take over. Assuming that you hold your pickles at the right temperature, which is basically room temperature or maybe a little lower, the bacteria eat carbs in the vegetables and convert them into lactic acid. And within a matter of days, they will have made so much acid they've lowered the pH in your brine and your food to below a pH of 4.6, thus arresting the growth of Clostridium botulinum, the bacteria that cause botulism. That's the big one you worry about with preserved foods. It's a horrible paralyzing disease with a 50% mortality rate without modern treatment and a 5 to 10% mortality rate with modern treatment. Botulism is a risk with non-acidic preserved foods. The whole point of lacto-fermentation is that it creates an acidic environment where botulism and other bad bugs cannot thrive, or botulinum I should say. That's the name of the bug.

Botulism is the name of the disease. Kind of sounds like a philosophy though. Now, I've been reading a lot of botulism lately. Well, it's really blown my mind. Anyway, that's why we use lactic acid producing bacteria to ferment our food for us, to make it acidic so that those bad bugs simply cannot thrive. Plus lactic acid is very, very tasty. And lots of other flavor compounds get created over the fermentation process. People have been doing this for thousands of years for a reason.

It takes no special technology. It's not the same thing as canning where you need to totally sterilize all of your instruments and squeeze all of the air out of the container and all of that and use heat. Lacto-fermentation just requires a basically clean pot. Clean potable water. Wash the vegetables first. Use the right amount of salt, which is easy now that we have scales. In the olden days, people would've developed volume-based recipes through trial and error. In the case of sauerkraut, European style fermented cabbage, you just cut up a cabbage, toss it with the right amount of salt, let it sit for a while to draw out the water from the cabbage.

If there's not enough water to fully submerge the cabbage solids, you have to add some brine that's at the right salt concentration, 2 to 2.5% by weight. Salt, not sodium. Salt. Right? Sodium is only one-half of salt, the rest is chloride. You have to create an anaerobic environment for the lactic acid bacteria.

And you just do that by submerging

All the food in water and brine, right? you just keep it submerged and that's anaerobic enough for the lactic acid bacteria.

You don't have to actually seal it up. In fact, you can't seal up the container because the fermentation process creates a lot of gas.

And a fully sealed jar might legit explode. The traditional way to do it is just in an open pickle crock with a weight that you use to hold down the food to keep it from floating up to the top and thus being exposed to air. It's just a weight that you put on the food. And that's it. That's it. That's all you do. It's easy to hold the right temperature because the basic temperature range that the bacteria like is the basic temperature range that we like. You just let it sit until it's sour.

You may get some bad fungal growth at the surface of the brine where there's air. Some fungi can survive in that salty, acidic environment as long as they have air. So you might get some molds growing on the surface of the brine. You watch for that. You skim it off when you see it. Generally, it's good to skim off anything that looks weird or gross on the surface. And then when the brine and the food is sour, it's pickled. It's done.

It'll probably last months as long as you keep it in a clean place, watch out for mold on the surface and all of that. How risky is this? Nobody really knows. We do know about some specific things that could theoretically go wrong. One thing that could go wrong is if lactic acid bacteria are not able to muscle out all of the other bugs in the early stages of the ferment. Maybe you didn't put in enough salt. Maybe you didn't get all the foods submerged in the brine. Maybe you just used some food or some tool or some hands that were just disgustingly dirty and covered in some awful pathogenic bacteria. And so that bacteria had a head start.

The test for this is to see if your pickles actually go sour. If they're not sour, don't eat them. And you can smell lactic acid. So you don't even need to taste it. It should smell sour. If it's been sitting in the brine for a few weeks and it's not sour, then something bad has happened. And you'll probably know it.

The food will probably start rotting by

Then.

 

All kinds of microorganisms will be at

Work, eating your food, and they will probably create disgusting smells.

You'll know. Probably. You can preserve food with just salt, no acid, but you need a lot more salt than just 2.5% by weight. That amount of salt just gives the lactic acid bacteria the advantage, the head start that they need to colonize the whole pickle crock, outcompete everybody else. And then over time to do what they do, eat food, poop out lactic acid, and lower the pH in there to the point where botulism, for one, will never be a risk. That said, if you were really dirty, if there were a lot of pathogenic bacteria in the pickle crock when you started, such as botulinum, then potentially that bad bacteria, let's go with botulinum, potentially, if the crock was colonized with a lot of botulinum upfront, they could potentially multiply and produce a lot of their pathogens, their toxins before the lactic acid bacteria really got going and lowered the pH to the point where the botulinum couldn't do their thing anymore.

That would happen, right? The pH goes down, botulinum they're either dead or immobile, right? But the toxins that they created in those first couple of days of the ferment, those would survive the acidic environment as might spores created by any spore producing bacteria that you've got in there, and botulinum is one of those.

I guess, in this scenario, there's a possibility you could get a sour pickle at the end that didn't smell foul, but it could still make you sick. For what it's worth, I can't find any case studies or anything on the internet about that ever actually happening. Another thing that could go wrong is that you might ferment the pickles in a reactive container like metal. The acid over time could leech a lot of metal into the brine and you could poison yourself that way. Though again, you'd probably notice. You'd notice the terrible metallic taste. You'd notice the corrosion on the inside of the bowl. Glass or ceramic are the classic choices for a reason.

Plastic is probably less risky than metal, or at least the risks of ingesting a lot of plastic are less well understood by scientists. That's the whole endocrine disruptor thing you hear people worrying about. I wouldn't do plastic unless in a survival situation. The other thing that can go wrong is that you can make perfect kimchi or sauerkraut or whatever, but then you get really careless as you store it. The experts generally recommend moving lacto-fermented pickles to the fridge once your desired level of fermentation has been reached. That's a controversial thing. Some people say, "Hey, I just leave it in the basement for months and it just gets better and better and better because it keeps fermenting.". You would arrest the fermentation process considerably by moving it to the fridge, but that's what the experts generally advise.

Ferment your food, then refrigerate it. You also got to worry about cross contamination with your pickles. We generally use pickles as condiments because they're too salty and too acidic to eat on their own. And that means we're constantly dipping back into the same container of kraut as we are cooking and touching other foods like beans sprouts or meat or other things that are likely to have some pathogens on them. And if you introduce new germs to the sauerkraut, it's possible that they could overcome the harsh conditions in there and thrive. The conditions generally get less harsh as you eat the pickles, right? You might not be keeping all the food fully submerged in the brine at that point. The lactic acid bacteria might be getting kind of tired running out of food to eat, less able to compete with fresh new bacteria. And Lord help you if you replenish the pickle jar with plain water rather than 2.5% brine.

You will lower the salinity of the entire jar. So the experts generally recommend that you don't keep lacto-fermented foods longer than say six months. You have to be mindful about what hands or tools you're sticking in there.

Keep them clean.

Also reinspect your kraut before you eat it every time. Check for fungus on the surface. Smell it. If it smells funky, throw it away.

Look out for dramatic color changes, that kind of thing. You could of course make the food a lot safer by cooking it. Boiling for 10 minutes, for example, will break down the botulism toxin. And getting the food a little bit hotter than boiling can actually kill the botulism spores. 250 Fahrenheit I think is where the spores die. But cooking lacto-fermented foods kind of defeats the whole point. The whole point is to deliver food with active, beneficial bacteria to your gut, where it is widely believed that they will make you healthier, only if they're alive when they get there though. You can't cook them and kill them.

Whether that they actually make you healthier is not a settled scientific question, but my sense is, the only question is how exactly do they make you healthier and to what extent? They probably do make you healthier. Also, lacto-fermentation softens food a whole lot, especially when you do it at warm room temperature. You can get firmer pickles if you do it at cool room temperature for longer. But regardless, lacto-fermentation softens food. And taking that and then cooking it could reduce it to mush. So you generally don't want to cook. That's not a good way of handling this. What are the odds that any of those bad things will actually happen to you? Well, in my experience, fungal growth on the surface of the brine is a near certainty that will happen.

It's a matter of watching for it and skimming it off before it produces a lot of some awful mycotoxin, mycotoxin, or mycotoxin. I can never remember how to say that. Let's go with mycotoxin. You want to get rid of that fungus before it has a chance to produce a lot of some awful mycotoxin or before it sends its mycelium deep down into your food. But of course not all fungi are dangerous. Some are our friends like yeast, which is often found in lacto-fermentations, at least on the surface where they can get the air they need. If you see like a milky white sludge on top of the pickle brine, there's a good chance that's yeast. And it's maybe unappetizing, but it's not harmful.

There's really hardly anything on the internet about people getting sick from lacto pickles. I can't find really any accounts of that happening on the internet. And I can't find a single account in the medical literature as searched on Google Scholar, which is pretty good these days. Usually when some kind of food poisoning is a problem, even a rare problem, you will find case reports on Google Scholar. 

And the answer is almost certainly not,

But i needed to find examples of solanine poisoning from people eating green potatoes.

And you will find a bunch of

Case reports on google scholar.

Most of them from decades ago, because this is a really rare thing.

And yet it has been written up because it does sometimes happen. Search Google Scholar for lacto-fermentation and illness, or lacto-fermentation and poisoning, or sauerkraut and illness, any kind of combination like that and all you find are papers about how these foods combat illness or may combat illness. It's totally possible that I'm just missing something. I am corresponding with several food microbiologists. One of them may end up having a case for me to look at. There's one such food microbiologist at the University of Houston named Dr. Jay Neal. He's real into pickles, writes about pickles, speaks about pickles.

And here is what Dr. Neal says, "Scientific literature has never recorded a case of food poisoning involving raw vegetables that have been fermented properly.". What are some examples of improper handling that may have resulted in documented illness? Well, according to Dr Neal's research, the majority of documented cases in the United States are in. Alaska. And it's a specific thing. It's indigenous Alaskan traditional pickled seafoods. Probably not a context that's anything like the context that you or I are in. And this part is pure speculation on my part, but I do wonder if maybe cold might be part of the problem there.

Lacto-fermentation might not even occur below 60 degrees Fahrenheit, 16C. So it's hard to do where it's cold. Dr. Neal turned up a 2012 outbreak in New York from fermented tofu being sold in bulk in a store, uncovered, unrefrigerated in water rather than brine. And he found a salmonella outbreak in North Carolina that came from unpasteurized tempeh. Tempeh and tofu. These are very high protein products made from soybeans. I imagine that raises the risks a bit.

Lots of really bad bugs love protein. And Dr. Neal notes that there were many opportunities for cross-contamination in the kitchen that might have caused that particular outbreak with the tempeh. Somebody who was sticking some chickeny hands into the tempeh for example. But that's all that one microbiologist was able to turn up when he went looking for cases of people being sickened by lacto-fermented foods. I'm still researching the topic.

But it sure seems to me that if you follow the recipe to the letter, keep everything reasonably clean, use your senses to check if the pickles have gone off, skim the fungus, you're probably going to be just fine.

And possibly much better than fine if

These foods are as good for us as we have reason to believe that they may be.

Now, let me swing back to Jade's question about reusing bits of vinegar mother or SCOBY for kombucha. First, let's remember that vinegar is totally different from lacto-fermentation. It's a totally different kind of fermentation. Vinegar is acetic acid producing bacteria, not lactic acid producing bacteria. That's why vinegar pickles never taste quite the same. Acetic acid just tastes, or smells at least, very different to us.

And SCOBY, the stuff that you use to ferment sweet tea into kombucha, that's like a whole mess of things. SCOBY is short for symbiotic culture of bacteria and yeast. So there's a major fungal component there that isn't important for vinegar or a lacto pickles. And the bacteria could be all kinds of things in SCOBY. Apparently, it's usually mostly acetic acid bacteria like in vinegar, though there could be some lactic acid bacteria in there as well. For those who don't know, the actual SCOBY or vinegar mother is a biofilm created by the bacteria. It's the slippery gelatinous disc that forms at the top of fermenting vinegar or kombucha. It's the actual colony of bacteria and other things in a little house that they built for themselves out of bacterial cellulose.

It's pretty gross when you see it for the first time, but it's where vinegar and kombucha come from. And to save some of the mother from one fermentation, to tear off a chunk of it and to throw it into your next batch of wine or sweet tea to make your next batch of vinegar or kombucha, well, that's the way that it's been done for thousands of years. Tear off a chunk of the mother, throw it into the next batch of wine. However, I probably wouldn't reuse the same mother or yeast or SCOBY or whatever more than say three times. That's just a guess, but that's what I'm going to say. Because every time you reuse it, you're creating additional risk for some kind of contamination or infection of your culture. That's a risk that people in the olden days simply had to live with. But you don't, so don't.

They had to live with the risk that they might just do a batch of pickles that does not come out. It comes out smelling rotten because their culture just kind of wasn't up to it. They had to live with that risk. But you don't, so don't. The mother or whatever that you're getting from the factory has been very carefully monitored by the company for any signs of microbiological contamination. You don't have that same ability at home so I just wouldn't risk it past three generations or so. Each time you get it out and you handle it, that's an opportunity for some wild microorganism to creep in and either spoil your food directly or just dilute your little colony with microbes that aren't doing the job that you need them to do. You might find that your microbial culture also just gets kind of tired as you reuse it across multiple batches.

This is something that beer brewers talk about all the time when they reuse yeast from one beer brewing to another. Even if they sterilize all their instruments and everything and they wash the yeast, which is a thing you have to do, you have to get the hops residues off of it, even if they do everything and they reuse their yeast from one brew to another, they hit a point after I think maybe even five or six generations, that few many generations, they hit a point where the yeast just kind of start to suck.

They just get bad at fermenting beer.

They can't get the alcohol high enough

Or it just takes them too long.

I don't know what the mechanism of

That is and i couldn't find any science on that when i went looking just now.

I wonder if it's maybe just like a function of inbreeding. Even if yeast don't always reproduce sexually, you're still dealing with an isolated population. And some undesirable mutation could creep in.

These things, they multiply and reproduce really, really fast. Like evolution happens fast on the microbial level. So you could get some kind of weird mutation that's in your isolated population and just makes it suck. You need a dose of fresh DNA from a distant population to reinvigorate everything. That's one possibility of what's going on. Two more things I want to say about this topic. One, the kombucha issue, SCOBY, you're going to love this. Oh, there's another little risk there with SCOBY and also I think potentially with vinegar, but I only hear about it with SCOBY.

And that is they're called vinegar nematodes. Vinegar nematodes. Google image search that at your own risk. Little bitty worms. Little bitty worms that can thrive and be very happy inside a SCOBY. They're apparently not actually bad for you, but you don't want to be drinking something that's full of worms, live worms. I mean, I realize gagh is best when served live, but yeah, if you get vinegar nematodes, you want to throw out the SCOBY or the mother if it happens in a vinegar mother. And now the last thing I want to say on this topic is, in the process of preparing the notes from which I am reading, text edit tried to auto correct lacto-fermentation to facto fermentation and loco fermentation.

And I think that's funny so I told you about it. Thom: Hey Adam, my name is Thom. I live in Chicago. I have a couple of quick follow up questions to this week's podcast. The first one is you talked about how more and more people are listening to your show through podcast apps as opposed to watching it on YouTube. I wonder how you feel about that shift as it potentially could affect your placement in the algorithm. Would you rather people listen to the podcast or watch it on YouTube? Is there any way that you, as a creator, can see the impact of that change? My second question is about the advertising model that you spoke about in the episode, I actually work in advertising, myself. A big part of that industry is tracking people and looking at their viewing habits, what they click on, what they don't click on.