The bottle

Bottles and the historical evolution of enological techniques

La Rioja, with a longitudinal extension of around 150 kilometres, produces wines which vary statistically in degrees of alcohol from 10% in the West to 16% in the East. The detailed and regular study of the evolution of these wines, which are produced in climatic regions varying from semi-humid to semi-arid, has been a most interesting and informative task. It has helped us to understand, from a historical viewpoint, the variation in consumers'tastes and the development of various wine producing regions.

We observed that usually, wines of less than 13% are spoiled by souring, whilst those of more than 13% do not become sour but mellow through the genesis of ethanal. The alcohol content conditions the deterioration of wines exposed to air. If there is a high alcohol content, the decomposition through oxidation will only result in mellowing.

But if there is a low alcohol content, this process of oxidation continues until souring. It is well known that a mellow wine can still be considered wine, but not so a sour wine. Taking these considerations into account, we have been able to outline a history of enology which easily explains the evolution and importance of the bottle.

There is a great deal of historical data which tells us that the most appreciated wines in Hellenic or Roman times were precisely those of the Mediterranean area, because their alcohol content of over 13· allowed for slow transportation in amphoras, wineskins and "pitacos" without hermetic seals. Northern wines, with less alcohol, were for local consumption because they would go sour before the following summer.

In the 17th century the glass bottle came into use, allowing for a hermetic seal. It was also noted that by burning sulphur, wine did not go sour in the barrels used for maritime transport. These two elements, the bottle and SO2, changed the historical course of taste and commerce in wine. It was now possible to protect wines of less than 13° from contact with air through a hermetic seal or by blocking with SO2 the oxygen dissolved in the wine. From that time on, wines with a moderate degree of alcohol could be transported and no longer had their market limited by time and distance.

The commitment between the bottle and the enologist

Many of the customs used in the art of winemaking originated from technical necessities which, in time, have been converted into tradition and prestige. In this sense, we understand that ageing wine, rather than with chronological intentions, was undertaken in order to stabilise it. Wine began to be kept in vats, casks and barrels in order to achieve the spontaneous separation of vegetable, microbial and crystalline matter before being bottled in a clean state. Later, it was associated with some event within the family. The wine from a specific year'harvest or bottling was kept for a special occasion.

The enological industry took these habits and transformed them into a commercial activity, creating a big business dedicated to aged wine contrasting to, and sometimes in dispute with, young wines or those of a recent harvest.

Once this point had been reached, the enologist acted in favour of stabilising the wine, preserving it in the cellar under specific control for a more or less prolonged period of time in order to ship it at a later date.

The events which took place in the world economy after 1974, specifically regarding the rhetorical figure of "the price of money", obliged those responsible for the economies of wine cellars to consider the cost of capital invested in ageing wine. Many of them opted for shipping young wines to the home and export markets. But others did not wish to do this without a prestigious stock of old wines, the most famous feature of winemaking.

Even regulations like those of the Rioja, which take ageing into account in cask as well as bottle, have obliged Rioja wine cellars to store enormous quantities of bottled wine.

This means a greater commitment to bottled wine by the enologist. Generally speaking, he used to control wine in the cellar before it was consigned to the consumer. Now, at a time when the businessman's aim is to sell "future", he finds himself increasingly having to guarantee, for longer periods, a wine which is actually under his control for less time.

Rhine, Bordeaux and Burgundy bottles

All of which necessitates more preparation, better equipment, more exact knowledge of the processes undergone by all kinds of wine in bottle and a precise knowledge of the climate and quality of the grapes.

Illumination and the colour of the glass used for the bottle

Although in normal storage bottled wine is kept in semi-darkness, it will inevitably be subjected to illumination which, depending on the colour of the glass, may have some effect on the stability of the wine.

For the ageing of red wine strongly-coloured bottles, verging on opaque, chromatic models no longer fashionable, are more convenient than those with green or bluishgreen tones and this is evident in the taste and aromas of aged wine.

In Champagne and also in still white wines the defect known as "goût de lumière" is presumed to be due to the photochemical participation of oxygen and the reoxidising "in situ" of riboflavin. Therefore, packing which guarantees protection from solar and fluorescent light is recommended. We may deduce from the intervention of riboflavin a potentially negative effect on wines which are kept a long time on sedimented yeast.

We have investigated two experiences. One is that of white wines bottled in colourless bottles with monochromatic illumination and the other is of wines bottled in different coloured glass. Special attention was given to the microbial control:

Wine	Bottle	Light	Colour after one month	Microbes
Control	Colourless	Atmospheric	0,11	37
a	Colourless	Blue	0,16	4
b	Colourless	Yellow	0,17	5
c	Colourless	Green	0,14	18
d	Colourless	Red	0,14	34
In darkness			0,15	28

Tasting gave the best result to the yellow bottle.

The variation in oxidation values was considerable in darkness and with green light.

The test was carried out on an unlabelled horizontal bottle.

The other study was carried out on different coloured bottles.

The results for red wine preserved in different toned bottles was as follows:

Bottle	Light received	Taste
Yellow-green	1.800 L/m2	Acceptable
Blue-green	700 L/m2	Acceptable
Yellow-black	160 L/m2	Pleasant

Using white wine, this test produced the following results:

Bottle	Light received	Flavour
Colourless	4.600 L/m2	Oxidation
Pale green	3.500 L/m2	Wooden tones
Amber I	1.450 L/m2	Pleasant
Amber II	1.400 L/m2	Pleasant
Green-yellow	3.350 L/m2	Slight oxidation
Green-yellow	1.850 L/m2	Pleasant
Green-blue	700 L/m2	Pleasant
Black amber	60 L/m2	Pleasant