In the winery the winter activity is of course wine-making. This combination of science, craft and a sprinkling of good luck is the crucial operation which turns the humble grape into something people like Oz Clarke can wax lyrical over. So, what is involved...? The first requirement is of course good disease-free grapes, as ripe as possible, and most importantly having the correct acidity at the time of picking. In the right hands the very best grapes will make the very best wine. That is not to say they will taste the nicest - indeed some fabulously expensive wines such as the German sweet dessert Trockenbeerenauslese are made from grapes that are virtually uneatable. In England we have to reconcile ourselves to the fact that we are too far north to get really ripe grapes as a normal crop. However provided we use vines developed for cool climates, and restrict ourselves to making suitable wine styles (mainly white, light and dryish still or sparkling types) we can make wines the equal of any in the world. Heavier reds and whites need more ripeness obtained from a longer summer season, and are only made in England with some difficulty.
It is the development over a long season that gives the grape its unique wine-making properties. From flower to harvest is typically 14-15 weeks, which enables the fruit to achieve very high sugar contents, and pick up all sorts of interesting flavours which increase the complexity of the final wine. Once the grapes have been picked and pressed we add a small amount of pectolitic enzyme to help clear the juice (or `must' as it is called at this stage). After 24 hours we rack the must (draw the clear liquid off any sediment), add yeast and a fermentation aid such as diammonium phosphate, and away it goes.
The fermentation typically takes 2-6 weeks, after which we allow the wine to settle. We try to extend the fermentation for as long as possible as a slow rate retains the more fragile aromatic components which will later give the wine its beautiful 'bouquet' or 'nose'. The fermentation generates heat which increases the fermentation speed, and here the English climate works in our favour because the cooler conditions at this time of the year slow the fermentation down without having to resort to cooling the vessels. It is very important to maintain strict cleanliness at all times, and as much as possible exclude air to prevent oxidation - we keep the tanks full and cover the wine with carbon dioxide. The yeast, having done its job, falls to the bottom of the tank to form a layer called the `lees', and the next stage is to rack the wine from above the lees. We then add finings of bentonite (a natural clay material) to aid settling, and filter and bottle the wine. This then is the basic process - familiar to all home wine-makers. Beyond this though there are many other small adjustments we can make to the wine to improve it. For example we can reduce the acidity, add sugar in legally limited quantities to increase the alcohol content (generally the increase is limited to a maximum of 3.5% alcohol), or impart oak flavouring either by using barrels or chippings. Our little laboratory is backed by specialist companies with very sophisticated (and expensive) facilities
Tasting the wine during making is very important, but by itself it is not enough. It must be backed up by chemical analysis. To give some idea of the complexities let us look at some of the processes involved:
· At harvest we need a particular acidity in the grapes - around 9gm/litre for still wine, and 10.5gm/litre for sparkling - expressed as equivalent to tartaric acid and determined by titration. Most wine-makers could not tell the difference between these two accurately by taste, yet it is crucial. During ripening the acid may only be at the correct level for a few days. This is where blending comes in - we have used the 11 different white grape varieties in our vineyard to produce the best possible juice (or "must" as it is called).
· Next there is sugar level. For most dry white wines we aim to produce about 11 to 11.5% alcohol, but for the sparkling it is lower (around 10.5%) as there will be a second fermentation giving about another 1.5%. The measurement is fairly easy to make using a hydrometer and standard tables.
· The use of sulphur as a de-oxidant is very important, but the concentration must be correct, and accurate analysis is essential.
· Removal of proteins is essential, and we use finings of Bentonite (a naturally occurring clay), but the amount must be correct - not enough and the wine will be unstable and cloudy, but too much will rob it of flavour and smell. We do a test for this.
· Then there are all the more complex features of the grape which come into play - such as whether it is neutral or aromatic in character. Will the flavour be improved by oak? Should the malic acid be converted to lactic acid by a process known as malo-lactic fermentation? This is where tasting reigns supreme!
|We get complex analyses carried out by a specialist laboratory, and a full analysis (costing about £50) is required for most competitions. Even professional judges can be fooled, and a wine with too much sweetness (for instance) to be classified as dry would have an unfair advantage if entered in that category in a competition.
The wine lies in the bottles in our insulated wine store for at least a few months to develop its full character. During this time we keep it in the dark, and as free as possible from temperature changes. English wine does not really need to be laid down over years like some full bodied Clarets or Sauternes, but it does need some time to mature. This can vary from 2 -3 months to perhaps a year or so. After this the wine will not really improve, but it shouldn't deteriorate for some years. However we prefer you not to keep it long, but drink it quickly and come back for some more!
Once we have made the decision to sell the wine we rinse off the outside of the bottles and label and box them. We hold only a minimum stock of boxed wine because it takes much more space to store boxed than in a bottle stack or 500 - 700 bottle crates. Also the temperature keeps more stable in a large stack.