Grape must is one of the key raw materials in winemaking.
However, not all the must obtained during the extraction process has the same characteristics.
Depending on how the liquid is extracted from the grapes, we can distinguish between free-run must and press must, two fractions with different properties and uses.
Understanding the characteristics of each allows for a better understanding of the winemaking process and helps determine how each type of must should subsequently be used in the winery.
WHAT IS MUST?
Must is the juice obtained from grapes by extracting the liquid they contain.
The method used in this process results in different types of must.
During extraction, two main types are obtained: free-run must and press must.
FREE-RUN MUST:THE FIRST MUST
When the grapes arrive at the winery and are crushed, some of the liquid is released by the grapes’ own weight, without the need to apply high pressure.
This liquid is known as the ‘free-run must’, which is the first portion of must we obtain.
This is a gentle extraction, carried out prior to pressing, which results in a must with distinctive characteristics.
CHARACTERISTICS OF THE FREE-RUN PRESS MUST
-Origin: obtained prior to pressing, mainly through the grapes’ own weight. This is a gentle extraction process.
-Characteristics: this is the highest-quality must; it is very clear, aromatic and refined, with a low level of solid residues.
-Composition: it has a lower concentration of polyphenols —compounds associated with colour and astringency— along with balanced acidity and a lower pH.
-Use: it is used in the production of premium wines.
WHAT IS PRESS MUST?
Once the free-run must has been obtained, the grape pomace still contains liquid.
To recover this, the grapes are subjected to a pressing process.
It is at this stage that we obtain a new fraction: the press must.
Unlike the free-run must, in this case the degree of extraction is higher and the transfer of compounds from the solid parts of the grape may also increase.
CHARACTERISTICS OF THE PRESS MUST
-Origin: it is obtained by forcefully pressing the skins and the remaining pulp from the free-run must using presses. This allows for greater extraction of liquid and compounds from the solid parts.
-Characteristics: it contains more impurities than the free-run must, as well as more polyphenols and a higher level of oxidation.
-Composition: it has a higher pH and lower total acidity, and may also impart more herbaceous or bitter notes.
-Use: it is usually vinified separately or blended in very carefully controlled proportions to add structure, colour or character to certain styles of wine.
FREE-RUN MUST AND PRESS MUST: WHY ARE THEY DIFFERENT?
Although both come from the same grape, not all fractions of must have the same characteristics.
The method and degree of extraction can influence their composition and properties.
It is therefore important to know the origin of the must when deciding how it will subsequently be used in the winery.
TWO METHODS OF EXTRACTION, TWO DIFFERENT CHARACTERISTICS
Free-run must and press must come from the same grapes, but the way in which they are extracted means they have different characteristics.
Understanding the differences between the various types of must provides a better insight into the winemaking process and the role each type of must plays in the winery.
At Bodegas Mamerto de la Vara, our experience of over 85 years in winemaking has given us an in-depth understanding of the characteristics of the various raw materials and how they influence each stage of the process.
This knowledge is essential for making the right decisions during winemaking and working to produce quality wines taking care at every stage of the process right from the outset.