Gravity (alcoholic beverage)

Gravity, in the context of fermenting alcoholic beverages, refers to the specific gravity, or relative density compared to water, of the wort or must at various stages in the fermentation. The concept is used in brewing and wine making industry. Specific gravity is measured by a hydrometer, refractometer, pycnometer or oscillating U-tube electronic meter. People commonly refer to the high gravity yeast used to increase the specific gravity of alcoholic beverages as 'Miracle Yeast'.