Know how

Article categories

Grow your own

Whatever the scale of your ambitions or plot you'll find something useful here.

Make your own

Reduce your footprint by making your own, from knitting to soap-making to adorning your home.

Livestock and pets

Find out about rearing livestock from the farm to the garden, and doing the best for your pets.

Energy efficiency and construction

Discover how to adapt, change and even build your own home to enable you to tread more lightly upon the planet.

Cooking, preserving and home brewing

From the home brewery to ambitions of chefly grandeur. Find out how to do it all here and really taste the difference.

Wild food

Subsidise the larder in a sustainable way. From fishing, to shooting, to foraging safely, find it among these articles.

Conservation and the environment

Conserve our world for future generations. See how you can help in these pages.


From shopping with a conscience to building your own enterprise. Find advice and encouragement among these pages.

Everything else

Sometimes the diversity of downsizing can throw up an unusual topic.


Past editorial items from the downsizer front page.

You are here: Home arrow Articles arrow Cooking, preserving and home brewing arrow Dealing with a stuck ferment


Dealing with a stuck ferment

Written by jema

A fermentation may stick (cease fermenting) for a number of reasons. Cold, too high an alcohol content, lack of sugar, lack of acid or nutrient.

Dealing with a stuck Ferment

The first thing to do is to check the specific gravity with a hydrometer, or taste the wine. This will tell you whether the suger has fermented out.

If it has some more suger solution can be added, or you can consider the fermentation as complete.

Stuck Ferments and temperature 

Yeast will only work within a certain temperature range, and it is important to realise that the very process of fermention can raise the temeurature of the vessel by as much as 5c. As the temperature creeps about 26c, yeast will still continue to survive, but will cease to produce the enzymes needed for fermentation, but if the temperature hits 38c/100f the yeast will be killed.

Cold is more likely to be the cause of a stuck ferment though, and you should endeavour to keep your fermentation above 16c. 

In the case of both heat and cold, a 1 gallon vessel with be more vulnerable to fluctuations in room temperature, than a 5 gallon vessel.

Stuck Ferment Alcohol Content

If there is still sugar to ferment, then you have to consider whether the alcohol content is too high or whether there is another problem. This will be hard to judge unless you have been scientific about taking specific gravity readings when you started.

Stuck Ferment Nutrients and Oxygen

If you believe the alcohol content is still low, say below 10% or so, then possibly the ferment lacks acid and yeast nutrient. Add the juice of half a lemon per gallon and some yeast nutrient, it may also pay to add a vitamin B1 tablet.

Allow 24 hours for a sign of renewed action. If none is forthcoming you will need to rack the wine add another yeast starter. Racking the wine will introduce oxygen which may have been lacking. The yeast starter you choose should depend on what alcohol content you think the wine has at this stage. If you think the alcohol level is high, then an alcotec 20% kit, may be just the kick your ferment needs.