Fledgling moonshiners often face situations when after a few days of setting the ingredients the wash stops fermenting and remains sweet. Worst case scenario—fermentation doesn’t start after adding yeast. Let’s go over the main reasons behind this problem and ways of reviving the wash.

1. Not enough time passed. Sometimes the wash won’t start fermenting right away. Depending on the materials used, temperature, yeast type, and methods of adding yeast to wort (diluted or not), visible signs of fermentation (foam, hissing sounds, sour smell, bubbling airlock) may become apparent only in a few hours.

Something is wrong if the wash is not fermenting after 6-8 hours after adding yeast.

2. The airlock passing. This is a common problem of many starting moonshiners who determine fermentation only by bubbled coming out of the airlock. If it’s not installed right, carbon dioxide will come out from other holes missing the tube. As a result, the airlock won’t show any signs of fermentation even if it’s ongoing.

Solution: check the airlock for pressure integrity by blowing through the tube leading to the container. If you hear a whistle, there’s a problematic area that requires sealing.

If the airlock is passing air, the fermented wash might turn sour, which will lead to a smaller yield and sour aftertaste. Using an airlock is essential.

3. Unfitting temperature conditions. The optimum temperature of wash fermentation with distilling yeast is 20-26°C, and the permissible range is 18-32°C. At a lower temperature, fermentation stops, yeast “fall asleep” but don’t die. High temperature can kill yeast due to boiling.

The fermentation process causes an increase in the temperature inside of the container by a few degrees (the bigger the container, the higher the increase).

Solution: if the wash stops fermenting due to the cold, transfer the container to a warm place. If the temperature is too high, create appropriate conditions and add a new batch of yeast. The wash should ferment in dark place or at least away from direct sunlight (you can cover the container with some fabric).

4. Wrong proportions. If the wash stops fermenting in normal conditions but remains sweet. The optimal sugar content in the wort prior to fermentation is 15-20% of the volume. High sugar content is a preservative that inhibits or even stops fermentation.

Another problem associated with an excess of sugar is a very strong wash. Most yeast strains stop working if ethanol content is more than 12-14% (some types of distiller’s yeast withstand 16-18%). Closer to the border of tolerance fermentation slows down. If there’s too much sugar, the wash will obtain maximum strength and cease fermenting sooner than yeast will stop converting sugar into alcohol.

On the other hand, low sugar content speeds yeast up and also significantly increases energy and time consumption during distillation because you’ll have to heat up more liquid. Let’s find a happy medium.

After diluting 1 kilo of sugar in water it takes up 0.6 liters of solution volume. To achieve wash. To achieve sugar content of 15-20%, add 3-4 liters of water (0.6:3*100=20% or 0.6:4*100=15%) and 100 grams of pressed or 20 grams of dry yeast per 1 kilo of sugar. Distiller’s yeast is added according to the ratios indicated in the label.

Yeast converts 1% of sugar into 0.6% of alcohol. The wash which is ready for distillation with the initial sugar content of 20% will contain 12% of alcohol (20*0.6=12). Any yeast will withstand such concentration.

Some moonshiners suggest adding 5-6 parts of water per 1 part of sugar, arguing that the wash will stop fermenting sooner, other things being equal (that’s true), and also the short fermentation time will decrease the number of hazardous substances, which are waste of yeast. In my experience, there is no difference in the quality of moonshines with different hydro modules (sugar to water ratio).

Solution: bring the ratio of the wash in line with the recommended values. If the sugar content is too high adding fresh cold water or heated to 30°C is enough, just don’t boil it to keep the oxygen.

5. Bad yeast. Active pressed yeast has a smooth pink, yellow or gray color and homogenous and moderately solid consistency. Its shelf-life in a fridge is up to 12 days. If there’s a putrid smell, the yeast is spoilt.

Pressed yeast

Dry yeast must be free-flowing. This can be checked by feeling the packaging. In case yeast was improperly stored, you should feel lumps or sticky consistency.

Solution: if the temperature and sugar content of the wash is normal, you should add new yeast, preferably purchased in another store.

6. Low-quality water. Oxygen and minerals contained in the water are required for the normal development of yeast fungi. That’s why you shouldn’t use boiled and distilled water or water passed through reverse osmosis systems for the wash. You’re better off using filtered, spring, well or bottled drinking water enriched with oxygen.

It’s possible that fermentation will stop if the water contains a high concentration of chlorine or other substances, which kill microorganisms. In other cases, low-quality water simply slows down fermentation.

Solution: add 50-100% of the initial water volume to the wash.


Moonshiner making ingredients