Must
Must or grape must is the juice of the pressed or ground mash. In common German usage, must is the juice initially obtained by pressing (Pressmost) and self-running off (Vorlaufmost), in which fermentation has not yet started. Simply put, it is the cloudy grape juice that has not yet fermented. It is the starting material for winemaking and is therefore of immense importance. One kilogram of grapes yields about 0.7 litres of must. The must is a good breeding ground for yeasts and bacteria because of the sugar and other nutrients it contains. Therefore, measures such as pasteurisation or filtration should be used quickly. It should also not ferment for too long at a certain temperature, otherwise bitter substances can form.