Dear Dr. Vinny,
Is there any risk to a wine’s quality, or the health of people drinking it, if the winemaker adds too much yeast or nutrients for the fermentation?
—Antonis, Greece
Dear Antonis,
Back to basics! Wine is what happens after the sugar in grapes is converted to alcohol with the help of yeast, through the process of fermentation. Some winemakers let nature take its course, allowing native yeasts (also known as “indigenous,” or “wild” yeasts) found on the grapes or in the winery to spontaneously ferment the grape juice without any manmade intervention required. But most wine is made by inoculating the juice with commercial yeasts , in the interest of achieving more control over the profile of the resulting wine.
Sometimes a fermentation gets “stuck,” when the yeasts slow down or stop consuming the sugars prematurely. There could be something in the environment getting in the way, like the temperature is too hot or too cold, or the equipment wasn’t completely clean, or the yeasts are not a good match with the grapes, or they are just too old and weak to continue on. In these cases, a winemaker can add a yeast nutrient, to give the yeasts a boost to keep going. The most common of these nutrients is diammonium phosphate, or DAP.
Back to your question: What happens if a winemaker adds too much yeast? Probably not much—there’s only so much sugar in the grapes for the yeast to convert, and that limits how much work there is for yeast to do. The extra, hungry yeasts without any sugar to consume will end up dying and settling to the bottom along with the rest of the lees and sediment. A winemaker would probably decide to rack the wine off of this extra sediment, so that the wine isn’t hazy and there’s no threat of any unexpected secondary fermentation.
Nutrients are slightly different. There are actually regulations to how much DAP a winemaker can add to a commercial wine in the U.S. and other countries—it’s plenty to allow for a healthy fermentation, but not in excess. These nutrients are useful, but they can increase the risk of volatile acidity and microbial instability (think spoilage organisms).
But the biggest reason it’s regulated is because too much nutrient additive can lead to an organic compound called ethyl carbamate, which is a suspected human carcinogen. Many fermented foods and beverages from soy sauce and kimchi to yogurt, olives, beer and whisky are all known to contain trace amounts of ethyl carbamate.
—Dr. Vinny
FAQs
There are actually regulations to how much DAP a winemaker can add to a commercial wine in the U.S. and other countries—it's plenty to allow for a healthy fermentation, but not in excess. These nutrients are useful, but they can increase the risk of volatile acidity and microbial instability (think spoilage organisms).
Can you put too much yeast nutrient in wine? ›
You also do not want to add excessive nutrients at the beginning of fermentation. Large additions of nutrients early in the ferment may lead to overvigorous fermentations and alter the aroma compounds produced by the yeast. In addition, residual nutrients in the wine may contribute to microbial spoilage during aging.
What happens if you put too much yeast in alcohol? ›
If we add an excessive number of yeast, the fermentation process will be robust and energetic, and this may result in an excessively active fermentation. It is possible for this to result in blocked airlocks, blow-offs, bursting bottles, or a fermenter that has ruptured.
Can yeast in homemade wine make you sick? ›
The short answer is no, wine cannot become poisonous. If a person has been sickened by wine, it would only be due to adulteration—something added to the wine, not intrinsically a part of it. On its own, wine can be unpleasant to drink, but it will never make you sick (as long as if you don't drink too much).
Can I add more yeast during wine fermentation? ›
Adding more yeast ensures that all the sugar is converted into alcohol, preventing the wine from being too sweet. However, it's important to note that adding too much yeast can lead to off-flavors in the wine.
Can you overdo nutritional yeast? ›
Too much nutritional yeast added too quickly to one's diet can cause problems with digestion, such as abdominal cramps and diarrhea. A high-fiber diet is good for digestive health.
Does yeast nutrient affect taste? ›
Yeast nutrients, judiciously applied, can speed fermentations and promote better attenuation, better flocculation, better yeast storage capability, and better overall beer flavor. As such they have become a standard part of the brewer's husbandry of yeast.
How do you know if you have too much yeast? ›
A person with an excess of yeast in the body may display skin problems like psoriasis, eczema, hives, and rashes. Psoriasis is a condition in which skin cells rapidly and uncontrollably replicate, causing the growth of scaly, itchy patches. Eczema is indicated by a red, itchy rash.
Does adding more yeast make more alcohol? ›
During fermentation, yeast begin with a growth phase. They increase their cell count before fermenting the wort into beer. Though proper pitching rates are valuable for a variety of reasons, the amount of yeast added is not the main factor in determining final ABV.
Why is my homemade wine so strong? ›
Some people who make wine from their own fruit or berries may add too much sugar and produce a wine that is very high in alcohol. This may be how the myth originated. However the fact remains that fermentation on it's own can only produce up to 20 percent alcohol.
This is a guide to correct some of the common problems in winemaking.
- Temperature is too high or low.
- Sugar level is too high.
- Alcohol level is too high.
- Lack of oxygen.
- Lack of nutrients.
- pH is too low.
- Volatile acidity (VA) is too high.
- Low yeast count.
Adding too much yeast to wine can cause a rapid, uncontrolled fermentation which can result in a wine that is: Overly alcoholic, harsh, and lacks flavor complexity. Prone to spoilage, spoilage yeast and bacteria can grow too fast and overpower other beneficial yeast and bacteria.
How much yeast nutrient do you add to wine? ›
Recommended dosage: 1 tsp of Wine Yeast Nutrient per gallon. Add to must or wort at the beginning of fermentation. Package contains 2 Oz. Explore our wide selection of Yeast Nutrient products, including Fermaid K, Fermaid O, Go-Ferm Yeast Rehydration Nutrient & more!
Should you stir wine after adding yeast? ›
Hello Charles, Once you add the yeast you will want to stir the fermenting wine must around as much as you can.
Can you have too much yeast in fermentation? ›
This may or may not be a good thing, depending on your intended style and flavor profile. If you over-pitch, or dump in too much yeast, your squadron of cells might over-accomplish its mission, thereby fermenting too fast and stripping the beer of much of its desired character.
How much yeast nutrient per gallon of wine? ›
Peynaud recommends a range of addition is from 10 to 20 g per hectoliter of must, or about 0.4 to 0.8 g/gallon.
Will adding yeast nutrients help a stuck fermentation? ›
You can add more of your original yeast or use a high attenuating yeast such as S-04 or US-05. Sometimes your yeast just runs out of energy. Adding in a new source of sugar can sometimes restimulate fermentation. Yeast nutrients, like adding sugar or fruit, can help return the nutrients that the yeast has depleted.
How often should I add yeast nutrient? ›
Our 5-gallon mead kits recommend adding 1/2 teaspoon yeast nutrient and 1/4 teaspoon yeast energizer at the beginning of fermentation and adding the same amounts once per day for the following 3 days. Be careful when adding dry powders to fermenting mead!
Does wine yeast nutrient go bad? ›
Typically, a well-stored yeast nutrient can last up to two years. However, this timeline isn't set in stone. Factors like storage conditions and exposure to air can shorten its lifespan. Over time, these components can degrade, especially when exposed to unfavorable conditions.
