Determination of the grape harvesting period
Controlling the grape ripening process is crucial in order to determine when to harvest, depending on the wine that has to be or can be obtained. At the end of the veraison (when grapes pass from the herbaceous to the ripening stage, with yellow or red skin colour) it is best to perform two inspections per week to determine a number of important factors of the ripening process. Take a sample using bunches or grapes taken from the same vine or the same area of the vineyard. Now crush the grape sample and, using a saccharimeter or a refractometer, determine:
1) Sugar content.
2) Total acidity and Ph.
Light white wines
Harvest the grapes before they are fully ripe.
Total acidity above 7 g/litre
Sugar content below 17° Babo.
Structured white wines
Wait for the grapes to fully ripen.
Total acidity between 5 and 6 g/litre
Sugar content above 20°
Babo Light red wines
Harvest the grapes before they fully ripen.
Total acidity above 6.5 g/litre
Sugar content below 18° Babo.
Aged red wines
Wait for the grapes to fully ripen.
Total acidity above 5 g/litre
Very low acidity and high Ph in red wines can cause fermentation problems.
Wine-making products or vinification
Products used during vinification to prevent alterations in the must by selecting fermentation yeasts and speeding up the decantation and extraction processes.
Sulphur dioxide and its derivatives:
useful for selecting the yeasts and favouring those with the best fermentation characteristics
- prevents bacterial alterations when vinifying bad grapes
- avoids undesired oxidisation of must in the early stages
- ensures regular fermentation
- enhances the varietal characteristics of the grapes
Pectolytic enzymes for white musts
- these separate the clear part of the must from the solid part (sediment)
Enzymes for red musts
- these extract the colour from the grape skins
- they represent the source of nourishment for the yeasts
- They stabilise the colour of red wines
- They prevent must oxidisation in case of bad grapes.
White vinification of precocious grapes
The white vinification of precocious grapes ( Chardonnay, Pinot, Sauvignon, etc.) is done by the fermentation of the must only without maceration of the solid parts of the grapes.
1) Quickly separate the must from the skins, to prevent tannin extraction
2) During pressing, to exhaust the marc, separate the “flower must” from the last fraction of crushing (“pressed”). The “flower must” represents 60-65% of the weight of the cluster. The potassium metabisulphite can be added before crushing or immediately after. Dosage is between 12 and 16 grams per 100 kg of grapes.
3) Immediately cool the must to a temperature below 18-20°
4) Clarify the “flower must” by separating the solid part consisting of pieces of skin and parts of the pulp which form a deposit (“clarification marc”). For this operation, use white must clarification enzyme in doses of 2-5 grams per hectolitre, dissolving this in a small fraction of must before adding to the mass to be clarified.
5) The next step is fermentation. The choice is between spontaneous fermentation and favouring this process by adding 20-30 grams per hectolitre of selected yeast. Above all, during the early days of fermentation, the fermentation temperature must be kept between 16 and 20°.
6) At the end of fermentation, perform the first transfer operation without adding products containing sulphur dioxide, which can instead, if so desired, be added at the time of the second transfer operation, 5-6 days after the first.
The diffusion of the wine
Ever since ancient times, wine has evolved as a part of Italian and European life, culture and diet. Brought from the East, the vine reached Italy around 1500 B.C. thanks to Aegean merchants and the new Greek colonist settlements. Later it spread, together with the expansion of the Etruscan civilisation, into central and northern Italy.
Praised by poets, historians and artists, wine played a lead role in ancient Greece and was considered as a privilege of the wealthier classes. Dionysus, the Greek god of wine, represented not only the inebriating power of wine, but also its social and beneficial virtues.
Wine-making spread and took root once and for all in Italy and Europe with the expansion of the Roman empire in the Mediterranean, when numerous large wine-growing regions came into being that still exist today. In those days too, wine-making was a painstaking process which favoured the development of various types of grapes and different growing methods. Barrels appeared for storing and shipping wine. Bottles were used for the first time and even a rudimental naming system was developed, just as soon as certain regions gained a reputation for their fine wines. As wine-making gradually became an increasingly more refined technique, its popularity increased and taverns became a common feature of towns and cities throughout the empire. The trade and organised distribution of wine came to a sudden halt with the fall of the Roman empire. The barbarian invasions and the break-up of state organisation interrupted trade flows and wine-making and its precious product found “refuge” inside monasteries.
Wine and Christianity
The rise of Christianity made wine an essential product in religious rites and the endeavours of the monks made grape-growing and wine-making flourish throughouEurope. The Benedictine monks, for example, became among Europe’s largest wine producers, with vineyards in the French regions of Champagne, Burgundy and Bordeaux, and in the German regions of Rheingau and Franken.
In that period, wine was considered as a major component of daily diet and people started to prefer strong and full-bodied wines. Wine continued to be popular in Europe throughout the early Middle Ages. Partly because drinking water was not safe, wine represented a privileged alternative drink at meals.
During the Renaissance, wine left monasteries and entered society. The nobles and merchants drank wine at every meal and kept well-stocked cellars.
From beer to wine
During the 16th century, wine became a more sophisticated alternative to beer and, as wine products began to diversify, consumers started to appreciate the concept of variation in their consumer habits. People began to enjoy discussing the positive and negative aspects of wine, more than they had in the previous centuries.
As production techniques improved, in the 17th and 18th centuries, wines of more refined quality appeared, glass bottles began to be used with cork caps, and the corkscrew was invented. It was in this period that the French wine industry began to flourish.
New forms of agriculture came into being and grape-growing manuals were published, with production and wine-making characteristics studied on a scientific basis.
Over the past 150 years, grape-growing and wine-making have been completely revolutionised as an art and a science. The introduction of harvesting machines has made possible the extension and productivity of vineyards. Though the wine-making industry is faced with the challenge of catering to increasingly bigger market demands while at the same time safeguarding the individual character of its wines, technology helps to ensure an adequate supply of quality wines.