Raw honey that has not been pasteurised so it contains live yeasts and enzymes. When diluted with water in warm temperatures the honey easily starts to ferment as the yeast start to consume sugars in the honey and multiply.
Raw honey naturally contains around 18% water. If the content is raised above 20% in a warm environment (21-40°C / 70-104°F) then certain types of yeast, naturally present and deposited by bees, can thrive and multiple so fermenting the honey. With the right yeast the result is delicious, ask any mead drinker. However, with the wrong yeast, the honey can be unpalatable.
Fermented honey, sometimes termed baker's honey, has a sharp taste due to the acetic acid formed, a slightly bready smell and a soft mouthfeel. While fermenting bubbles can be seen in the honey and the fermented honey can retain a frothy appearance. Fermented honey on breakfast muesli with natural yoghurt is delicious. Fermented honey is also thought to be extremely good for the gut biome.
However, according to UK law, beekeepers can't legally make or sell fermented honey. Although we are unaware of a prosecution, it is also likely to be illegal for bars to make and serve fermented honey in cocktails.