Do Bacteria Survive Your Stomach Acid, The Difference Between Fermenting and Rotting, Plus More Fermented Food Q & A : Exclusive Excerpt from “Cultured: How to Make Healthy Fermented Foods at Home”

Friday Sep 23 | BY |
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kevin gianni fermented foods talk
Whatever you… make sure you never, never, never, make this face when someone is taking a photo of your presentation. (Eucalyptus Speaker Series, Stillheart Institute)

This excerpt is from our new book “Cultured: Learn to Make Fermented Foods at Home” which contains over 70+ fermented food recipes. Click here to learn more!

Today, to end this week’s fermented food journey, I’m going to close with some frequently asked questions taken from “Cultured: Make Healthy Fermented Foods at Home.”

In these excerpts, I cover questions like:

  • Do bacteria survive the journey past your stomach acid?
  • What is the difference between fermenting and rotting?
  • Do alcoholics need to worry about eating fermented foods?
  • What is the right temperature to ferment foods?
  • How long do you ferment foods?
  • Should you ferment at home or buy fermented foods from the store?
  • Why do some experts say eating fermented foods are bad for you?

Let’s get started…

Do Bacteria Survive the Journey Past Your Stomach Acid?

Despite how powerful stomach acid is, many bacteria do make it into the gut, which you’ll definitely understand should you take a trip to Mexico or India and mistakenly drink the water. Not good!

This all largely depends on the strength of the strain of the bacteria in question, and it’s the strongest ones that make it through to help repopulate your gut. As such, it’s important to make sure the foods you’re eating have a wide variety of live, healthy, strong bacteria, which is one of the main reasons we prefer cultured ferments.

What’s the Difference Between Fermenting and Rotting?

If the thought of eating fermented foods makes you a bit queasy, you’re not alone. There are indeed some people for whom the thought of eating anything more than a week old is simply gross. This is a frame of mind worth changing, however, as fermented foods are so far from the rotting foods that might be coming to mind for you. In simple terms, fermenting is great and safe, while rotting food is awful and downright dangerous! Although there is indeed a thin line between two processes, they couldn’t be more different in the results they produce. Let’s break down that distinction.

Putrefaction is the process that causes food to rot, and when this occurs, harmful bacteria run amok on the food in question, breaking it down to an inedible and terribly stinky state. These bacteria rob your food of life. With fermentation, however, you’re exercising some degree control of the environment in which the food is placed; when this is done correctly, beneficial bacteria are produced that inhibit the growth of harmful bacteria. This preserves and infuses the food with beneficial bacteria, allowing you to eat it well past its usual shelf life.

So if you’re worried that fermented foods have spoiled or rotted in any way, rest assured – fermentation has banished the bad bacteria that can make you sick, or at the very least, get your gag reflex going.

Do Alcoholics Need to Worry about Fermented Foods?

Great Question! Alcohol is a by-product of the fermentation process, although this isn’t the case for foods such as kefir and miso. In most fermented foods, alcohol is produced in such minute quantities that it will have no effect on your body. I would, however, be careful with kombucha. Many store-bought brands of kombucha can produce levels of alcohol up to 3%, and sometimes may not be labeled to reflect this. In fact, Whole Foods Market pulled all of the kombucha on its shelves in 2010 due to the fact that the labels didn’t state how much alcohol each bottle contained. [1]

Many brands have since accurately updated their labels, so make sure to inspect each bottle you might decide to buy. At the end of the day, whether or not to buy kombucha will be a personal decision.

Finding the Right Temperature For Your Fermented Food…

Fermentation is a delicate process, and it’s very important to be mindful of maintaining the right temperature in the area where you choose to let your ferments sit.

I’ll give you an example: my wife Annmarie and I tried our hand at yogurt once. We were using a yogurt maker, which we figured would be pretty straightforward as it maintains a constant temperature of 90 degrees. Everything would have been fine had we not left the yogurt maker close to a window that let a steady stream of sunlight in. What we ended up with was most definitely not yogurt.

This principle also applies if you’re living in a colder climate. If this the case, you’ll want to set your ferment in warmer area of the house, or else your ferment may not grow at all.

Fermentation Times – How Long Does It Take To Ferment Something?

Here’s a tricky subject: how long should you let your ferments sit for? There’s no firm answer for this, but that’s all part of the fun. Effective fermentation times vary entirely based on how much prebiotic you add and what temperature your ferments maintain. With experience however, you’ll come to recognize this as an art, knowing what to look for and taste for.

Of course, personal preferences come into play here as well. Many foods will have sufficiently fermented in the course of a week, but that time can be extended or reduced. For example, in the case of coconut kefir, you might like it very bubbly, which requires a longer fermentation time; less bubbly doesn’t need to sit as long. Similarly, most vegetables break down more and develop a stronger, more vinegary with time; as such, if you prefer milder flavors, you might not want to allow your ferment to sit as long.

The best thing to do aside from consulting recipes is to taste your food at regular intervals, every 3 or 4 days. This will allow you to experience and understand the relationship between time the various stages of the fermentation process, in addition to allowing you to determine what kind of taste is pleasing to your taste buds.

Fermenting at Home Vs. Store-bought Ferments

Just as we took a moment to consider why producing your own ferments was preferable to buying probiotic supplements, you should give some thought as to why fermenting at home would be preferable to buying ready-to-eat ferments from the grocery.

Right off the bat, there’s an immediate advantage that shouldn’t require much consideration: it’s so much cheaper to do it yourself! Many things are cheaper DIY style, but this is especially the case with fermented foods, as many of them can very pricey.

For example, I remember once buying a jar of sauerkraut from a store for about $9. This was the good stuff, sauerkraut that hadn’t been heated to pasteurize and “purify” it, allowing all of the beneficial bacteria to remain intact. I was quite pleased with my purchase until I came home and realized I could literally ferment almost four times that amount of sauerkraut for the same price with very little effort.

Of course, if you’re buying fermented foods from your local farmer’s market, there’s a good chance that those are recipes that have been fine-tuned over hundreds of batches. That’s fine, and it shouldn’t discourage you from trying your own ferments at home. It allows you to support your local farmers and get an idea of the standards you can hope to achieve with practice.

If you’re buying from a larger chain supermarket, try to look for information on the label about their fermentation practices. You definitely don’t want pasteurized ferments, as they won’t provide the health benefits that you’re seeking. If they don’t, however, and the rest of the information on the label checks out, feel free to give it a go. One advantage is that these foods will likely have been subject to extremely strict processing guidelines, giving you the assurance that the food you’re getting was prepared in a very hygienic setting.

Some Health Experts Say Fermented Foods Are Bad For You… Are They Right?

As with every other aspect of life, people will always disagree on some topics. In fact, this is especially the case with medical science. Just as there are countless health advocates who tout the beneficial effects fermented foods have on the human body, there are also those who dismiss them as anything more than interesting culinary preparations.

Modern medicine loves to dismiss anecdotal evidence, but in the case of fermented foods, it’s absolutely silly, even haughty, to deny thousands of years of information speaking to the health benefits of fermented foods from cultures around the globe. Furthermore, most of this information has been confirmed by modern, scientific studies done by reputable researchers.

For us, the answer is clear: fermented foods are awesome!

I want to know your thoughts: What is your most pressing question about fermented foods?

Be sure to get a copy of “Cultured,” or at least read more about this incredible new book that is literally FLYING off the shelves. It’s over 70+ fermented food recipes contributed by culinary experts – the best of the best. 🙂

Here’s where you can get a copy now…

Live Awesome!

Kevin Gianni

Kevin Gianni is a health author, activist and blogger. He started seriously researching personal and preventative natural health therapies in 2002 when he was struck with the reality that cancer ran deep in his family and if he didn’t change the way he was living — he might go down that same path. Since then, he’s written and edited 6 books on the subject of natural health, diet and fitness. During this time, he’s constantly been humbled by what experts claim they know and what actually is true. This has led him to experiment with many diets and protocols — including vegan, raw food, fasting, medical treatments and more — to find out what is myth and what really works in the real world.

Kevin has also traveled around the world searching for the best protocols, foods, medicines and clinics around and bringing them to the readers of his blog — which is one of the most widely read natural health blogs in the world with hundreds of thousands of visitors a month from over 150 countries around the world.


Comments are closed for this post.

  1. Melissa Pacheco says:

    Can you use Raw unfiltered Apple cider vinegar to ferment veggies?

  2. nilsholgerson says:

    Is sauerkraut in a jar still alife?
    Can i ferment food instead of cooking?

    i ask mayself what is my most needable question on fermentation?

    i wanna do sauerkraut. Does it become sttinky if ido it indoors.

    How clean have tthe jjars are? How do i corretly clean the jars for fermentation. soap hot water?

    Is apple cider vinegar raw?

    When i can use my ownn spit to ferment things?
    Can i just use a ffruit chew it in my mouth spit it in a jar. pour water over..add some herbs maybe antibacteriel and then let it go.

    How to find trust tthat it will become a goodie?

    Can i use ffermentation as energy source. like yeast and sugar?

    And at least

    i have a heart question…*****
    THIS is a heart question****

    I have done Netttle Beer.

    stinging Nettle beer

    is this healthy?
    And its made with cooked nettle water
    sugar added. thenn yeast on a piece of whitebread.

    is there a healthy way o ferment nettles? Nettle infusions?


    anotherr question is alcohol always dangerous? or is ffruit sugar and fruit acid sometimes more dangerous?

  3. Linda says:

    Look at the harmful effects of fermented foods at

  4. Attila says:

    “Do helpful bacteria survive the travel through stomach acid?”
    According to what I’ve learnt reading the book the Ph Miracle, acid levels in our stomach vary depending on the type of food we’ve just eaten or we are about to eat. The body prepares an optimal environment for the digestion of the food we’re about to eat. If it anticipates a need to digest mostly protein, it’ll start producing more stomach acid as the digestion of meat requires an acidic environment. On the contrary if there is no need for an acidic environment for an upcoming digestive job, there’ll be little to no acid present in the stomach – such as when we drink a glass of water or eat a bowl of salad. Or fermented fruit and vegetables for that matter.
    If you avoid eating protein with your fermented food, there’s no need to worry about the bacteria being killed off in the process.

  5. Cherie says:

    I hope to get the book soon. When I have eaten fermented food my digestion is soooo much better. Thanks for all your time.

  6. Jon says:

    I am curious about why good bacteria grow on foods during fermentation, but bad bacteria and yeast grow on foods that are just left out of the fridge at room temp. Your statement on the distinction between rotting and fermentation in the article above didn’t provide an answer to that question, so I still have no idea why fermentation attracts good bacteria and just leaving food at room temp unaltered attracts bad bacteria and yeast.

  7. Velda says:

    Good question, Jon. I would like to know the answer to that myself. Also, if a person with diabeties, high blood pressure, and kidneys that are going bad, begins to eat fermented foods, is it possible that could improve health in those areas? I know you cannot make medical claims, but I am wondering in general, from others’ experiences, if it could have a positive affect on the health in those areas – or not affect at all.

    Good article, as usual, Kevin. Thank you,

  8. Thomas says:

    “Pathogenic bacteria, viruses and toxins produced by microorganisms are all possible contaminants of food. However, microorganisms and their products can also be used to combat these pathogenic microbes. Probiotic bacteria, including those that produce bacteriocins, can kill and inhibit pathogens.

    Fermentation is one way microorganisms can change a food. Food fermentations are ancient technologies that harness microorganisms and their enzymes to improve the human diet. Fermented foods keep better, have enhanced flavors, textures and aromas, and may also possess certain health benefits, including superior digestibility. For vegetarians, fermented foods serve as palatable, protein-rich meat substitutes.

    Fermentation in food processing typically is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. A more restricted definition of fermentation is the chemical conversion of sugars into ethanol. The science of fermentation is known as zymurgy.

    Fermentation usually implies that the action of microorganisms is desirable, and the process is used to produce alcoholic beverages such as wine, beer, and cider. Fermentation is also employed in the leavening of bread, and for preservation techniques to create lactic acid in sour foods such as sauerkraut, dry sausages, kimchi and yogurt, or vinegar (acetic acid) for use in pickling foods.”

    Bottom line: the TYPE of bacteria is what differs spoilage (rotting) from positive fermentation. 🙂

  9. LynnCS says:

    Velda #7. Dave the Raw Food Trucker has a number of talks on “You Tube” about improvement in those areas by juicing and drinking Kombucha each day. He tells of an amazing experience. Personally my experience in just a couple of months is that everything is getting better. If you’re new, it’s a good idea to research detoxing too, because getting better seems to produce some detoxing ill feelings in a lot of people. Sticking with it is what seems to be the key. I am sure Kevin’s book will help you make some of those things yourself and you can try. It can only help, in my experience. I have been a vegitarian and macrobiotic 31 yrs. Mostly vegan for quite awhile and now raw for only a few months. Macrobiotics eat some kind of pickled or fermented food with every meal.

  10. Elizabeth says:

    If you don’t do it exactly right, is there a danger in getting sick? Are fermented foods O.K. for children?

  11. Amy says:

    I’ve heard the debates on both sides of this issue, too. Like you said, Kevin, the personal experiences speak for themselves!

    I, personally, feel great when I’m eating fermented food. I’m glad your putting information out that will help others properly make these great foods at home!

  12. Ira Edwards says:

    Raw milk has natural lactobacilli that protect the milk from other bacteria. Milk that is a day or two old is less likely to have any surviving disease organisms. In time, the milk sours – faster at room temperature or warmer – and is a healthful fermented drink. Pasteurizing kills the natural bacteria, and the milk picks up whatever is in the air, and it spoils. Don’t drink that.

  13. Becky says:

    Is this the same as japanese ‘pickles’? Also does anyone know how long you can keep miso? If it’s fermented, I guess quite a long time?

  14. Candice says:

    I’m a huge fan of fermented foods, but have yet to try my hand at making my own. The expense along is enough to encourage me to give it a try. Now, if I can just get my family to join me . . .

  15. carmen says:

    I live in North East Brazil and it is almost impossible to get hold of anything to help with fermentation (any suggestions?). There is very little choice of vegetables as it is, mostly fruit – which I can´t take advantage of because I have serious acid issues and can´t eat acidic fruits and tomatoes. Also the temperature here inside the house is normally 27-30 degrees centigrade all year round. Would I be able to ferment vegetables safely under these conditions?
    … and does your book have enough recipes for basic vegetables as it is impossible to get even simple stuff like miso, or soya beans products like tofu at the big and small supermarkets. Trying to get anything shipped from outside Brazil is a nightmare and mostly doesn´t arrive.
    PLEASE HELP as I really need it having suffered from chronic inflammation and heavy phlegm in the stomach,thorax and throat region which has kept me in a generally weak state for the past 29 years!…

  16. Thomas says:

    Go to YouTube ( and type in “fermented vegetables”. There are enough instructional videos to keep you busy for quite some time.
    Good luck with your condition. Have you thought about just swallowing probiotics? If you can’t get them locally, ships them to Brazil and everywhere globally.

  17. sheri says:

    an inexpensive product is the perfect pickler, we have been making fermented veggies with this and loving it. I can’t wait to try Kevin’s recipies with it.

  18. Heather says:

    Carmen, I made fermented vegetables and coconut water when living in the tropical Caribbean. It still works, just watch over your ferments because they may go a lot faster in a warmer climate. Best of luck!

  19. Missy says:

    I just received live water kefir grains. I am currently fermenting my first batch.

    My question concerns is it safe for an alcoholic to drink water kefir? How can you say it is safe even though there is a small amount of alcohol when fermented? Isn’t alcohol just that…alcohol? Or does it have to do with the way the body processes the small amount? For example, the body won’t recognize it as alcohol?

    I’m suffering from candida and want to incorporate water/coconut kefir into my daily routine. The last thing I need to do is relapse from drinking it! So, even though you say it is okay, I need to double check for my own paranoia:)


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