The weight of a liquid as compared to an equal amount of water. The specific gravity of water is 1.000. As fermentation commences, the SG decreases. A wort with an SG of 1.050 weighs 1.050 times an equal volume of water. See also original gravity and final gravity .
Brewers use a hydrometer to measure SG .
A small volume of wort mixed with yeast. Used to increase the yeast population before introduction into the main wort. Liquid yeast cultures should always be used with a starter, as the population is not nearly sufficient to achieve ideal fermentation. Use of 2 packages of dry yeast gives sufficient population such that a starter is not required. See sanitary .