`must` means unfermented grape juice obtained by crushing or pressing; Grape juice in barrels or vats before being transformed into wine. It is therefore clear that there is no single must and that, in order to understand the composition of the must, we must take into account the different treatments to which the grape and its juice are subjected in order to obtain a reliable raw material for fermentation. In a ~ or wine, there is both free and bound, hydrogen particles.pH is a measure of the number of positively charged free hydrogens present. Grape must contains a variety of nitrogen sources, of which ammonium, primary amino acids and small peptides are the most important for yeast growth. The nitrogen state of grapevine and grape must directly or indirectly influences many primary and secondary metabolites of grapes and yeasts such as alcohols, acids, esters, carbonyls, volatile sulfur compounds, terpenes, phenols and other compounds (Rapp and Versini, 1996; Bell and Henschke, 2005). In addition, YAN also indirectly influences the metabolism of grape compounds that form the basic composition of wine and its varietal character. Therefore, in order to optimize fermentation to produce the desired flavor profile, it is necessary to measure the YAN. Figure 58.2 illustrates the influence of the nitrogen state of the must and the effects on the quality of the wine. The term «must» is derived from the Latin term vinum mustum, which means «young wine». Must is the name given to freshly squeezed grape juice that contains the skins, stems and stems of grapes.

The must is the first stage of winemaking after the harvest of the grapes of the vine. The mixture is thick and opaque and varies in color depending on the grapes pressed, ranging from dark purple to light brown. Winemakers can use individual grape varieties or a blend of different grapes, depending on the type of wine they produce. The wort has a high glucose content (on average between 10 and 15%) and is then used as a sweetener in many different cuisines. The solid part of the must is called «pomace » and represents between 7 and 23% of the total weight of the must. The length of time the marc remains in the juice plays an important role in determining the final characteristics of the wine. Fermentation begins in the must from the yeast present on the grape skins, and the process is determined by how long the must sits. Once the desired time is reached, the juice is drained from the pomace and the pomace can be returned to the vine to be used as fertilizer. Sometimes some of the wort is stored as a «sweet reserve», which is added to the wine as a sweetener before being bottled. How the winemaker handles the must determines many of the final characteristics of the wine, including colour, acidity and tannin content.

~ Crushed grapes and juice fermented into wine (including seeds, stems, skins).~yThe unpleasant smell of a wine that has come into contact with old or poorly cleaned wooden barrels. The integration of gene expression with metabolite profiles throughout fermentation has proven to be even more informative when it comes to finding specific genetic traits responsible for a particular metabolic/aromatic profile (Rossouw et al., 2008). This integration of data has enabled multivariate statistical models that can be used to predict genetic changes that may promote the increase or decrease of specific metabolites and resulting aromas. The proteome profile of wine fermentation could also provide clues to the selection of yeasts that might be present in starter cultures, in fact certain enzymes (e.g. polygalacturonase, β-d-xylosidase and proteases) commonly produced by non-succomy yeasts can improve wine quality and simplify some winemaking processes (Fernandez et al., 2000; Strauss et al., 2001). The winemaker can also opt for a combination of destemmed grapes and whole grapes and opt for 100% pressing of the whole grape. When the grape stems are green and young, they give the wines green, vegetal and vegetal notes. The ripe stems give the wines produced spicier and sweeter aromas. ~ is one of the first steps in winemaking and refers to freshly crushed fruit juice that contains grape skins, pips and stems. The solid part of ~ is called marc. Read moreN. ~ The intermediate step of the grape liquid, which is neither grape juice nor wine.

Nose tasting term. Wine is judged by taste (palate), but also by smell (nose). Musty: With a dissuasive musty or musty smell. The result of a wine made from moldy grapes, stored in poorly cleaned vats and barrels, or contaminated by a bad cork. Systems biology tools provide valuable tools for characterizing the physiology of wine varieties. Although limited knowledge about the genetic makeup of non-Saccharomyces yeasts hinders the use of some molecular tools, microarrays have been used to characterize gene expression and genotyping of Saccharomyces yeasts in industrial wine, which often have genomic profiles not present in laboratory strains (Marks et al., 2008; Pizarro et al., 2008; Hauser et al., 2001; Hughes et al., 2000). This approach leads to the identification of genes that confer beneficial properties to industrial yeasts.