For cultivation and enrichment of yeasts. Dissolve 33.28 gms in 1000ml distilled water. Add 2.35gms or (1.9ml) of Glycerol. Mix well. Gently heat to boiling with gentle swirling and dissolve the medium completely. Sterilize by autoclaving at 15 psi (at 121°C) for 15 minutes. Mix well and dispense as desired. Appearance: Yellow coloured opalescent solution in tubes -: pH (at 25°C): 4.8 ± 0.2
WORT BROTH is used for cultivation and enrichment of yeasts developed by Parfitt in 1933. The medium contains Malt extract and Peptone as sources of nitrogen, vitamins, amino acids for potential microorganism’s growth. Maltose, Dextrin and Glycerol are the sources of carbohydrates. Dipotassium hydrogen phosphate provides buffering capability. The microorganisms other than yeasts are suppressed by the low pH 4.8 of medium. To increase the selectivity of the medium add 12ml of filter sterilized 10% lactic acid (TS 049) which makes the pH of 3.5. Addition of Glycerol reduces the water activity from 0.999 to 0.95, thereby reducing bacterial growth.