Oenology is the science of wine making.
Wine making is the art of selection and application of processes to achieve a desired outcome, ultimately from fruit (grapes) to wine.
Wine making is a very natural process whereby yeast, either indigenous to the environment (floating in the air) or innoculated into the juice or must (crushed grapes and juice) by the wine maker. It is important to realise that when fruit in nature, loses the integrity of it's surface, either by hail, pests biting, too much rain splitting the fruit, or any other means, the yeast in the air lands on the exposed fruit that is rich in sugars, and begins to metabolise them, converting the sugar into alcohol and carbon dioxide, the two main bi-products of fermentation.
In wine making, it is the controlled process that maintains the fresh and desirable characters that will benefit the wines quality.
Grapes are harvested at the end of the growing season based on the conditions that will make quality wine. This includes the grapes ripeness, including the sugar content (known as brix or beaume'), the flavor profile and development of the grape, and can also include the weather conditions.
Before grapes are received at the winery, in some cases they have had an addition into the holding vessel, usually a picking bin of 1 or 3 tonne. Potassium metabisulphate is added to help protect the grapes in transit from oxidisation and any undersirable fermentation 'kicking off'. When received at the winery, the vessels are weighed and then poured by forklift into a receival hopper with an orga seated in the valley. By controlling the speed of the orga, the grapes are pushed and fall into a spinning de-stemmer (a cylinder with holes for the grapes to fall through and paddles pushing them through), removing the berries from their bunch stems, these then fall into another hopper with a spinning 'crusher' at the base. The crusher holds two rotating grooved cylinders set approximately 5-10mm apart. The juice and crushed grapes are then pumped into either the press for white grapes making white wine, or a fermentation vessel for red wine. After this point, many different factors can be employed.
However the basic principles need to be noted are;
Fermentation- The conversion of sugar into alcohol and carbon dioxide (CO2)
Beaume- The sugar content of the juice generally measured either by, refractometry or specific gravity, converts closely to the percentage of alcohol in the resulting dry wine wine. eg. 13 degrees beaume' will become 13% alcohol by volume in a dry wine. Also the lower the beaume' or ripeness i.e. the sugar accumulation, the higher the acidity and lower the pH. (Brix is the more common and accurate measurement however it is far simpler to understand using Beaume')
Dry Wine- The yeast converts all the sugars in the juice to alcohol.
Residual Sugar- The yeast has not yet converted all the sugars in the juice to alcohol. This leaves the wine with sweetness. Common method for making sweeter wine styles. Remember there will be a lower alcohol due to this non-conversion.
Free Run Juice- The collected juice that runs freely from the grapes post harvest. If a wine is made from this separately, it results in higher quality wines. Usually referred to in white wine making.
Pressings- The extraction of juice remaining in the pressed skins when extra pressure is applied. Usually regarded as a lower grade and harder, less fine wine resulting. However sometimes some very good quality wines result due to this extraction.
Sparkling Wine Production- Traditional Methods
The three traditional grape varieties used for Champagne production are Chardonnay a white grape, Pinot Noir a red grape, and Pinot Meunier a red grape. However there are many different percentages used to create the final Cuve'e (blend) which may not include all the varieties. e.g. 60% Chardonnay, 30% Pinot Noir, 10% Pinot Meunier.
We must also acknowledge that other parts of the Wine World have been making sparkling wine using many different grape varieties for many years for which to be explored.
For sparkling production, in order to not end up with a pink wine or rose' colour (in some cases desirable), the red grapes must be pressed immediately after crushing. It is important to note that almost all red grape varieties have white juice. So by using this method of pressing the crushed fruit, the juice that is extracted is white and won't impact the color of the Spakling Wine. The juice is then fermented and becomes a base wine. This base wine is similar to other finished white wine however the qualities desired for sparkling production include lower ripeness, usually close to 9-10 degrees beaume' and hence is higher in acidity giving sparkling wine that renowned crisp taste.
(In the most well known styles and brands.)
Styles of sparkling wines vary greatly however and can be made from very dry (brut de brut) to sweet (riche or sec). The flavour profiles include a fine linear racey style that is sharp generally referred to as an apperitif style, through to a bold and complex meld of yeasty and toasty aromas and flavors, sometimes referred to as an autolysed style and of course the sweeter style sometimes peachy, turkish delight or glace' strawberry flavours. And everything in between.
Using the traditional method, base wines (something akin to regular still table wines) are blended, then added to the sparkling bottle.
Essentially at this point, to create the bubbles in the bottles there needs to be a secondary fermentation that is captured in the bottle to saturate the wine with carbon dioxide, responsible for the bubble, and give us the pleasurable experience we know. When this is complete, the lees (the now floculated and accumulated dead yeast cells on the side of the bottle) needs to be disgorged. Through a process called riddling, the lees is slowly shaken into the neck of the bottle where it is then put 'on point' (the mass is sitting in the inverted cap) and then submerged in a brine solution of alcohol and water (presenting a lower freezing point) which quickly solidifies the lees mass and a small amount of liquid. The crown seal is then released forcing the frozen mass out due to the natual pressure now inside the bottle. The bottle is then topped with the same cuvee, or any amount of recipes of legal variations to create a style that a brand is known for, then recorked and caged as we know it. This is a very simple explanation of traditional sparkling production. Please explore this further at your leisure.
The making of white wine is generally a relatively quick process.
Grapes are received at the winery, crushed and pressed into tanks and fermented to the desired point of dryness, and then are modified to meet the wine makers requirements which can include blending, fining, acid additions, filtration and bottled for market. A process that can be performed over a month if required. Exceptions are secondary barrel ferments called malolactic fermentation whereby the sharper malic acid (apples) in the wine is converted to a softer rounder richer lactic acid (butter). Also barrel maturation imparting flavour characters and bottle ageing which is suited to some styles and varieties like Riesling and Semillon in particular.
Similar to white wine production only that the wine is fermented on the skins for different periods of time, thereby extracting the pigment from the skins, and generally most reds go through the secondary fermentation process and most are put into oak barrels or derivitives there of including submerging staves (planks) into wine tanks or adding 'tea bags' of oak shavings) for different periods of time to help enhance the flavour and structure of the wine.
Red wines also carry their own preserving agent being tannin extracted from the seeds of the grapes and the oak barrels. This preservative generally helps with the longevity of wine in the bottle and helps them gain the regard for cellaring.
Desert Wine *Next on the To Do List*
Fortified Wine *Coming Soon*
Please note that this is page is for general knowledge and may help in the understanding of your appreciation of wine. We will also be updating this page as comments come in and more enquiries are made.
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