Yeast

Yeast is probably the most important ingredient to a winemaker – it is a vegetable matter, a living cell that will multiply in the correct environment. Its needs are simple, just sugar and acid in water at a temperature of 70–75°F/21– 24°C. Yeast will break down the sugar, and use it, firstly to multiply itself, and then, when the colony is active and healthy, to turn the sugar into alcohol and carbon dioxide.