Looking at the principles of winemaking and options we have in order to make the style of wine we require.
Harvesting begins when the grapes have reached optimal phenolic and sugar ripeness. Harvesting the grapes too early can introduce unripe, 'green' notes into the wine, while grapes that are harvested too late can make for a flabby or jammy wine. Weather needs to be taking into consideration, for example when a storm is approaching, it might be best to bring in the grapes slightly underripe than taking the risk.
Marchine harvest vs hand harvesting
These machines beat the vines with Ruber sticks, shaking off the grapes onto a conveyor belt that transfers them into a holding bin. Making harvesting quick. The negative would be damaging the grapes before they get to the cellar that can lead to oxidation of the juice, unwanted materials and grapes can end up in the fermentation vessel.
Hand harvesting is more gentle and can be done on slopes, job creating and people can be trained to only pick the optimal ripe grapes and leave unwanted materials in the vineyards.
- Crushing and pressing
Upon arrival in the cellar the grapes can be destemmed, removing all the grapes from the stems to avoid transferring more tannins into the wine. Using the stems to assist with drainage channels that increase the efficiency of the passing process.
For the white wines, the free-run juice is augmented by juice extracted by pressing the grapes. Pressing releases juice from the cells on the inner surface of the grape skins, along with aroma, flavour, and polyphenols. Traditional wine press consists of a slatted basket with spaces between the slats and a lid that is screwed down to press the grapes. Pressing inevitable involves the release of bitter polyphenols, and the winemaker must strike a bale between volume and quality.
Gentle press are more often used, grapes are loaded into a horizontal, perforated cylinder with a rubber bladder running through the centre. The bladder is then inflated with air so as to exert gentle pressure on the grapes.
Wine is a result of fermentation by yeast cells of sugar into ethyl alcohol, or ethanol.
There are many different species of yeast, and within each species, several genetically distinct strains. The yeast most commonly used in winemaking is Saccharomyces cerevisiae, which is efficient at fermenting sugars into ethanol and able to survive high levels of ethanol waste product.
The unfermented grapes juice is called the must, and it is transferred into a fermentation vessel. It can be an airtight stainless steel tank to an open-air top or oak barrel. The winemaker can either inoculate the must with a commercially produced yeast culture or rely on the yeast cells on the grape skins and winery equipment to start a 'spontaneous' fermentation. With the latter fermentation the winemaker are unable to pick the yeast they want and the yeast are normally several species of yeast, results in more complex flavours and aromas. When inoculating with a commercially yeast, the winemakers have more control over the fermentation process and a desired aroma and flavour can be enhanced.
In most cases, the fermentation naturally comes to an end when the yeast run out of nutrients, typically after one-to-two weeks. The wine has then been fermented 'to dryness' , meaning that there is very little sugar left in it. In some cases resulting in a wine with substantial residual sugar. Alternatively, the fermentation an be artificially terminated by filtering out the yeasts or killing them by adding sulphur dioxide or increasing the temperature.
The simplest wines are bottled almost immediately after fermentation. Most wines, however, benefit from a period of post-fermentation maturation. Chardonnay can be kept in contact with lees, which consist primarily of dead yeast cells, fro some time after fermentation. Lees again adds to the texture and complexity of the wine and imparts notes fo yeast, bread, brioche and biscuit.
Wine is commonly matured in oak barrels, which, although watertight, allow small amounts of oxygen to filter Tinto the wine. Too much oxygen can damage a wine, but a small amount, has 'n number of beneficial effects, including enhancing colour stability and intensity, dispelling reductive and vegetative notes, making tannins soft.
Wine is, in fact, one of the most complex of all beverages, the fruit of the soil, climate and vintages, digested by fungi through a process guided by the culture, vision and skill of Martin and I.
(article extracted from 'The concise guide to Wine and blind tastings" Burton; Neel