The decision to harvest comes after several instrumental analytical controls that allow the evolution of the concentration of sugars, acids, polyphenols and aromas to be followed precisely and rigorously until the best moment is identified. Harvesting by hand makes it possible to select the best bunches, which are placed in wooden or plastic crates and placed on lorries or tractors to be transported quickly to the cellar, where the bunches will be further selected.
To transform the grapes into must, crushing or destemming systems are used for red wine making, while grapes for white wine making are pressed directly. In red wine making, soft crushing is carried out using machines with toothed cylinders and gently crushes the grapes, which are simultaneously sent into a perforated cylinder. Inside, a shaft equipped with paddles detaches the grapes from the stalks, which are ejected. Grape yields in must are between 55 - 75 %. In white winemaking, which takes place without the presence of the marc (= skins and pips), the delicate composition of the grapes requires more attention: to improve quality, the grapes are pressed directly using membrane presses made of slotted steel in which whole bunches are placed. Inside the press, a rubber membrane compresses the grapes, which release the juice without tearing the skins and stems (thus preventing them from releasing unpleasant components), and the MUST FLOWER is obtained.
Must is the juice obtained from crushing/pressing grapes, in which hundreds of substances are dispersed in water. The amount of sugar in the must can vary greatly because it depends directly on the quantity present in the grapes. In musts intended for dry wine production, this is generally between 18 - 25 %, in the case of over-ripened grapes it increases to 30 %, and in the case of raisining it reaches 40 %. The more the must is rich in sugar, the more the wine will have a high alcohol content, unless a sweet wine is produced, because then the action of the yeasts will be blocked to limit alcohol production and maintain a high residual sugar content.
Lo sugar is essential for turning must into wine. The total acidity of the must is the sum of the fixed and volatile acidity, generally between 0.7 - 1.1 %. FIXED ACIDS are present: tartaric, malic, citric, oxalic, glycolic... VOLATILE ACIDS: acetic (must be present in a very low quantity). I polyphenols are decisive in characterising the wine's personality: colour, structure, tannicity and longevity depend on the quantity and type of these. The pectins are present in small quantities, except for musts obtained by pressing grapes attacked by noble rot. The vitamins are essential for the yeasts to be able to develop and perform their fermentation processes to the best of their ability. Vitamin B1 (added before fermentation) is the most important, both as a growth factor and thus as an accelerator of alcoholic fermentation, and for its ability to prevent the formation of substances that can combine with sulphur dioxide. The nitrogenous substances are used to help the yeasts and their quantity in the must varies depending on many factors such as planting density, climate, fertilisation techniques and yield per hectare. The enzymes are proteins that increase the speed of chemical reactions.
I LIVES are single-celled microorganisms responsible for alcoholic fermentation. On the skins and stems are the beekeeping yeasts that start fermentation processes quickly, but have little tolerance for both sulphur dioxide and the ethyl alcohol they produce (which is good because it stops the production of unpleasant substances). I elliptical yeasts are responsible for the transformation of must into wine, they are the saccharomyces (brewer's yeast). Often used in wineries are the selected yeastscapable of adapting very well to different production processes. I varietal yeasts are able to release the aromatic precursors naturally present in the grapes in which they are used in order to enhance their primary aromas. Within the must, oxygen is essential for the multiplication of yeasts, and nitrogen for the production of higher alcohols and esters.
Moulds develop and damage grapes under conditions of high humidity. Botrytis cinerea, also known as grey mould, is the only exception. This, under particular soil and climatic conditions, turns into noble rot and contributes to the creation of the famous mildew wines. Since the mould feeds on sugar, mildewed raisin wines are less sweet than normal raisins.
are microorganisms that are smaller than yeasts and generally harmful because they can cause disease in wines. Their development is very unlikely given the perfect conditions in the cellar. Only certain strains of lactic acid bacteria are useful because they are used for malolactic fermentation to make the wine softer by transforming malic acid into lactic acid.
Before vinification, the must is treated to maintain or enhance certain characteristics in order to make it clearer, more stable and of better quality. The treatments applied in the case of a must vinified white or red are different.
CLARIFICATION = only for white winemaking, is favoured by enzymes that break down pectin molecules, substances that enrich the viscosity of musts, especially those obtained from botrytised grapes or harvested late in the harvest, sometimes making filtration more complicated.
CLARIFICATION = addition of gelatine, bentonite, casein, silica gel followed by centrifugation or gentle filtration. Operation aided by cooling, whereby the must is kept in insulated double-walled tanks in which a cooling solution circulates.
DECANTION = takes place without the addition of clarifiers: low temperatures (6-10 °C) decrease the solubility of solid particles and cause them to flocculate and precipitate more easily. Pectolytic enzymes are often used, which allow a more targeted precipitation without altering the sensory profile of the must.
SUGAR DEGREE CORRECTION = more is needed in the presence of unfavourable vintages and therefore imperfect ripening. In Italy, with the exception of liqueur wines, no sugar may be added, but the must must must be either cut with musts richer in sugar, or the must must must be supplemented with concentrated must, obtained by the partial evaporation of water in a vacuum to avoid caramelisation of the sugars and organoleptic alterations. In quality production, rectified concentrated must (MCR) is used, obtained by evaporation under vacuum followed by subsequent rectification to obtain a final product of water and grape sugar that in no way changes the sensory profile of the must to which it is added, but only makes it sweeter. The dumb must, obtained by centrifuging and filtering an already partially fermented must, has a sugar content of 18 - 20 %. Any diminishing correction is only made with less sugar-rich must cuts.
ACIDITY CORRECTION = addition of tartaric acid. During alcoholic and malolactic fermentation and ageing, acids tend to be transformed, resulting in a decrease in colour vibrancy and taste freshness. A good level of acidity protects the must from disease.
CONCENTRATION / REVERSE OSMOSIS = expensive process that concentrates the liquid without altering its organoleptic characteristics.