My Wine’s Fermenting Without Adding Any Yeast

Wild Yeast On GrapesWhy is my grape juice bubbling and I have not added my yeast yet.

Name: Jerry R.
State: PA
Hello Jerry,

The simple answer is your juice is naturally fermenting because of wild yeast. This is why a wine will ferment without adding yeast, at all.

Yeast is everywhere: floating in the air, landing on plants and animals. It is ubiquitous to the nature in which we live. Your grape juice either picked up some wild yeast somewhere, or it started naturally fermenting from yeast that were on the grapes themselves.

Most of the time, vineyards selling fresh grape juice to home winemakers will treat it with sulfites such as potassium metabisulfite to destroy any of the wild yeast and to temporarily protect if from fermentation and spoilage. This would eliminate any chance of a wine fermentation occurring from the natural yeast that was on the grapes.

But there is still the issue of the wild yeast that is floating around. From the oranges sitting on the kitchen counter to the cat who just came inside for a little nap, the sources of yeast are many and unstoppable.

Once a few cells of the wild yeast make it to your wine juice, then it becomes party time. A wine fermentation will ignite with the natural yeast. Slowly, the yeast will start to consume the sugars and use that for energy to multiply themselves into a larger colony. As the colony becomes larger the growth will slow down and the focus will turn to the productions of alcohol. This is how a wine ferments without adding yeast.Shop Wine Yeast

What is described above is no different than what happens when you add a domesticated wine yeast. This begs the question, “why add yeast at all?” The answer is simple, with wild or natural yeast you never know what you are getting. Yeast is not just yeast. There are thousands of yeast strains, and with each strain are an endless number of varying mutations.

With a domesticated wine yeast: 1) you know what you are getting, 2) the strain is kept consistent, and 3) the strain has been bred for a specific characteristic, such as alcohol tolerance, flavor profile and such. Domesticated wine yeast pack more firmly on the bottom of the fermentation vessel as sediment so you can more easily rack the wine off of it. You may want to take a look at a wonderful article we have on the reasons you should use a domesticated wine yeast.

Now that you know your wine fermentation is from natural yeast. What should you do?

Fortunately, there is a simple remedy for such a situation. Wild or natural yeast are not very resilient to sulfites, and sulfite is the active ingredient in Campden tablets, potassium metabisulfite and sodium metabisulfite. All you need to do is add a dose of any one of the above, and the wild yeast will easily be destroyed and no more natural fermentation. Wait 24 hours, then add a domesticated wine yeast to the juice. During this 24 hour period you should leave the grape juice uncovered, or at most, covered with no more than a thin towel. Shop Potassium BisulfiteThis will allow the sulfur to release as a gas and dissipate. Once the domesticated wine yeast has been added, you should see a renewed fermentation start within 24 to 36 hours.

Having a wine ferment from natural yeast is not a horrible thing but it is something you’d prefer not to have. It’s like rolling the dice with Mother Nature. The important thing to understand is that a wine fermentation can occur without adding yeast, but there is something you can easily do about it.

Happy Winemaking,
Ed Kraus

Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.

24 thoughts on “My Wine’s Fermenting Without Adding Any Yeast

  1. What options are there for people that are allergic to sulfites? Anaphlactic reactions are not a pleasant experience, I’d like to try making my own, have a problem with commercial wines from time to time

  2. I am a natural home wine maker. I am not a professional and I don’t use any test insturments, I let the grapes do everything, as the fermentation process speaks for itself….time in a bottle. I used Blue Lotus in the bottling process with a pinch of metabisulfate in the 5 gallon batch, and its good after 3 years…worse thing happened during racking one 5 gallon batch went brown on me because I sloshed it around…oxygenated it, but It came back after bottling on its own 🙂

    Since I am not selling and have to keep customers I marketed to happy, I am all natural and it works and 8 cases of beautiful great smooth wine….not hot alcoholic skittle juice from modern wine making techniques.

    • Thanks for your tips, John! I’m just getting into making natural wine at home. I had only done wine kits before and added all the packets, sulfites, etc, but have learned to love the taste and funkiness of natural wine and want to switch over fully. What do you mean when you say you used blue lotus in the bottling process? And does the metabisulfate do anything in particular that you choose to keep it?

      Thanks in advance for your help!

  3. Christian Churches use wine and bread baked without yeastfor the Holy Communion sacrament . How can I make wine without yeast fit and acceptable for sacrament?

    • Abiodun, unfortunately, we do not have any information on how you can make wine without any yeast.

    • Hey, you can make wine without adding yeast. The fermentation should have two stages: stage 1. Add all ingredients (no yeast) and leave it for seven days. Second day stir for a minute and do the same on the seventh day.

      On the eighth day transfer by sieving it to another jar and keep it for 51 days without disturbing. Then bottle it. Do it all hygienic way.

  4. After having followed the advise of Kill the wild yeast and use domesticated for 3 years, I decided to ‘roll the dice’ to see what my natural yeast on the grapes would produce. 2 separate 1.5 gallon batches, 1 of which my partner included even the hard immature grapes. Mine was sweetened for alcohol potential of 14%, partner’s for 17%. The mostly mature grapes completed primary in 6 days at which time I decided to add energizer to partner’s batch which took 2 more days to complete primary. Both now are 6 weeks into the total process and have acceptable tastes (we both enjoy our batch rather than the other’s – LOL). Unless they age poorly, I will attempt next year with no added sugar (if the birds will let them ripen enough).
    Question – Next year can I expect the natural yeast to be very similar to this year’s or another ‘roll the dice’??

    • JJM, there is no way to predict how the natural yeast will react from batch to batch. It looks like it will just be another “roll of the dice.”

  5. Ed. Last brew accidently self started fermentation because I stupidly added some extra fruit to the must after the bulk was treated. So I let it go as was. Happily it produced a reasonable wine but low alcohol. I say happily because in previous years some small batches that I deliberately let self ferment resulted in very bad tasting wine. I presumed that whatever the wild yeast was it was not good for tasty wine. So the “roll the dice” with natural fermentation obviously can be a a natural disaster as well.

  6. Hallo Sir.
    My First batch Wine’s Fermenting Without Adding Any Yeast
    data :

    Starting on March 5 just use grapes and sugar without any yeast.
    On March 14, i strain it all
    now it is 8 days in a condition that the airlock is not blubling.
    From the beginning of the process do not use Sodium Metabisulfite
    Please advise! What I should do?

  7. So Ed, if I make organic wine do I/ should I wash the grapes first? Won’t that remove some of the natural yeast?

    Receipe for white organic wine please?

    • James, yes if you wash the grapes it will remove the natural yeast. I am sorry, we do not have a recipe for organic wine.

  8. Hi Ed I’m making my first ever batch of plum wine well actually I’m making my first ever home brew altogether :).
    I have just done my boil and added yeast nutrition to the mix as it instructed in an article I read.
    But now do I add dry yeast to it aswell or not, will it be over yeasted if I do this.
    I’m worried I may have messed up. 🙁

    • Matthew, if I understand what you are saying correctly, I think there is a little confusion. Yeast nutrient is not yeast, it is nutrients for the yeast. You still need to add yeast.

  9. I enjoy reading these questions and your responses ed, and im no expert wine maker, but ive experimented with several yeasts, including bread yeast etc, and with and without various sugars added(white, brown, honey), and with various fruit and with store bought fruit juice.

    And i found out something by accident that works well to produce both good “sparkling wine”(although technically “new wine”) and also tasty fruity vinegars.

    Just buy a half gallon of your favorite juice warm and pour a small glass out and then take a few swigs from the bottle and set it on the counter with the cap loose and let it rip(and i do do not add sugar, just 100% juice in the half gallons although gallons would work too obviously).
    I have done this in texas and in chicago and usually within a day or 2 the fermentation will start and you will get very fine bubbles and from that point on after the first day of fermenting you have a very champaign like beverage with fine(tiny bubbles and light with very little foaming and very little sediment) carbonation that is not too sweet and obviously it gets less sweet by the day, but then i sometimes just keep topping off and for a few days at least you can hold it in a similar state.
    The alcohol content is not very high obviously but its a very tasty beverage thats a little less sweet than the juice from the reduced sugar but also the “experienced” sweetness is also reduced by the carbonation, just as a “flat” coke will nearly KILL YOU with its sweetness, the carbonation makes it bearable.
    I am presently doing the same thing with old orchard organic blackberry lemonade and it is coming out great but if i let it finish it will have higher alcohol content because of the massive quantities of sugar that they put in tart lemonade.
    If you want the vinegar, just let the wine fermentation complete and leave the top loose for a few months and you will have very tasty vinegar of whatever flavor juice you started with.
    I will caution though, if the alcohol content is not high enough and/or the transition to vinegar isnt strong enough acidwise, it appears possible to farm botulism IF YOU SEAL THE BOTTLE AFTER THE 1ST FERMENT, SO DO NOT SEAL THE BOTTLE as it continues on to vinegar, AS BOTULISM CANNOT GROW WHERE OXYGEN IS PRESENT according to scientists that know better than i. Lol(although ive accidentally ended up with the cap sealed and gotten vinegar and used it and didnt die…luckily…).
    and of course ed, your comments and/or additions to this are more than welcome as you obviously have more knowledge than i.

  10. Wild yeast were used for years. Some German monastery was making beer. Like this. Monks know how to make some great beer. Over time, it was decreed that no beer should be made certain months of the year. Bad tasting brew. The wild yeast strains were more prevailent than others, making the taste of the brew from month to month diffrent.

  11. We have 5 gallon of pear that will not ferment. We gave added extra yeast, put it in a warmer place used a yeast starter. It is doing nothing. It’s been 5 days with no activity. Help!!

  12. Over fermentation? I’ve 6 Gal of freshly crushed Zinfandel grape juice ( crushed 20 Nov 2020 ). It is now approx 5-6 weeks later and it still appears to be fermenting! Small bubbles still slowly rising and keeping the airlock busy. Wine is in basement of home where temperature is in low 55-64 degree range.

    Is this “normal” ?
    Do you recommend treating wine with campden tabs , waiting 10-14 days, then adding a commercial yeast? If so which tyeast do you recommend?

    Sorry for all the questions – this is a first attempt at making wine “the natural way”.

    Thanks for your comments and advice!

    • The rate of fermentation can be very dependent on how warm or cold it is. It would ferment much faster if you got the temperature up to 70F. When you treat the wine with Campden tablets, you only have to wait 24 hours before adding the yeast. During this time, cover the fermenter with nothing more than a thin clothe towel. Like a tea towel.

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