Must Production and Treatment

The grape clusters cut from vine stocks using grape shears are cleaned of rotten and dried berries and then, as fast as possible, separated from the stems. This is done in a roller emsher 

The left over stems, skins and seeds provide the pomace. It is used as feed or fertihzer, or is fermented to provide pomace wine. This is consumed as a homemade drink and is not marketed. Pomace brandy is obtained by distillation of fermented pomace. The average must yield is 75 1/100kg grapes. Of this, 60% is free juice (must), 30% press-must and 10% must from the second pressing. 

The fresh, sweet must can be treated with sulfur dioxide (50 mg SO2/I) to suppress oxidative discoloration and the growth of undesirable microorganisms. In order to remove undesirable odors or off-tastes, the must is treated with activated charcoal and, when necessary, is clarified by separators or filters. In general, sulfurization before fermentation is dispensed with if the material is faultless and pure culture yeast is used. If required, the must is pasteurized by a short heat treatment (87 °C/2 min). 

The addition of sugar to and deacidification of must will be discussed in 20.2.5.4. 

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