Dissolve the active dry yeasts (ADY) in 10 times their weight in a 50/50 mixture of water and must at a temperature between 35 and 40°C. Example: 500 g of ADY, in a mixture containing 2.5 L of water and 2.5 L of must at 37°C.
Leave for 20 minutes then slowly homogenize the yeast starter. If the temperature difference between yeast starter and must is 10°C or below, add the yeast starter directly to the must. Otherwise, double the yeast starter with must, wait 10 minutes, homogenize the mixture slowly and add to the must.