Santa Margherita

The composition of the grapes and, consequently, of the must represents the element that undoubtedly has the most significant effect on the production of quality wines.
The components that make up the must, obtained by “squeezing” the grapes (crushing, pressing, etc.), are essentially the same in all cases. What varies considerably, thus resulting in fruit that is completely different from the point of view of quality, is the quantity of each constituent and the variability in the relationships between them, depending on the degree of ripeness of the grapes, the growing area, the clone and grape variety, the weather conditions, cultivation techniques and extraction methods used (many of these elements will be conditioned by both enological and commercial factors).
Broadly speaking, then, we can identify the following components:
•    water: this is the principal element, in the order of 700-830 g/l, depending on whether there is a more or less substantial presence of sugars owing to overripening and/or drying of the grapes;
•    sugars: on average, there are 150 g/l (not particularly ripe grapes) to 280 g/l and even higher (overripe or dried grapes), with similar correlations between glucose and fructose (G/F=0.9-1.1);
•    organic acids: depending on the degree of ripeness, these range from the 12-15 g/l of not very ripe grapes (with a probable prevalence of malic acid) to 5-6 g/l in very ripe grapes (with a prevalence of tartaric acid);
•    polyphenolic substances: these are made up of flavonoids (anthocyanins, tannins) and non-flavonoids (phenolic acids, volatile phenols) in the order of 0.1 – 3 g/l, depending on whether it is a must from white grapes or from red grapes in maceration;
•    pectic substances: due to the presence of pectins, pectic acid, gums, etc., in the order of 0.2 – 2 g/l;
•    nitrogenous substances: fundamental in the subsequent stage of fermentation, these are made up of ammoniacal nitrogen, amines, polypeptides and proteins in the order of 0.2 – 1.5 g/l
•    mineral substances: these are both in the form of cations, such as calcium, potassium, sodium, iron, magnesium, etc., and anions, such as sulphates, phosphates and chlorides (1 - 3 g/l);
•    vitamins: there are just traces of these (well below 100 mg/l);
•    aromatic substances: present in varying quantities depending on the grape variety (whether it is aromatic or not); in the best cases these will reach a few hundred mg/l.