Yeast is a fungus that is used in baking, brewing, and winemaking. It is responsible for the fermentation process, which converts sugar into alcohol and carbon dioxide. To ensure that your yeast is still active and will produce the desired results, it is important to check its activity before using it.
There are a few simple ways to check if yeast is still active. One method is to dissolve a teaspoon of sugar in a cup of warm water. Then, add a teaspoon of yeast to the mixture and stir. If the yeast is active, it will start to foam and bubble within a few minutes. Another method is to sprinkle a teaspoon of yeast on top of a cup of warm water. If the yeast is active, it will float on the surface of the water.