When does honey ferment, and how can we tell that it has fermented?
Question

 
Honey may ferment over time, so how does a muslim know when it is permissible and not permissible to consume ?
Praise be to Allah.Honey does not ferment, even if it is left for many years, so long as the moisture in the jar does not increase beyond 19-21%.
Fermentation may be detected by smell, and by a change in taste and the appearance of air bubbles in the honey, in which case there will be the smell of alcohol. This is what a specialist told us.
It says on the website of the Cooperative for the Development of the Apiculture Industry in Riyadh:
Honey Fermentation

Honey will ferment if the moisture in it increases beyond 19-21%, especially when cutting away honey that is not ripe, or adding water to it.
Ripe honey could be preserved for a long time without fermentation. As for honey that is not ripe, or honey that is kept in places where moisture is high, it is exposed to the risk of fermentation due to the impact of some yeasts that carry high concentrations of sugar. The sources of these yeasts include pollen, air and dust.
The yeasts that are present in honey may secrete enzymes that turn sugars into alcohol and carbon dioxide. These alcohols may be broken down, due to the effect of bacteria and oxygen in the air, into acetic acid and water.
Fermented honey loses its natural smell and taste, and develops a sour smell. Foam and air bubbles may develop in it. End quote.

Conclusion:
If pure honey is stored correctly, it will not ferment.
And Allah knows best.