Types Of Wine How External Factors Can Affect Your Wine

By Chloe Alster

The components that influence how a type of wine develops fall broadly into two categories. The more ‘internal’ factors are things such as the variety of grape, the amounts of sugar and the tannin that can be extracted. More external factors are the yeasts, growing conditions, barrels and so on. Whilst it cannot be argued that the principal influence is the combination of grapes these external factors cannot be ignored.

The difference between grape juice and wine is alcohol which is created by yeast fermentation. In many types of wine the yeast itself is actually a factor in the flavor and the strain of yeast certainly affects the amount of alcohol. Most yeast naturally dies off at certain levels of alcohol bringing a natural end to the fermentation, some like Tokay yeast, have a higher tolerance and so make stronger wines. When the yeast dies off and fermentation is complete the wine is still cloudy and full of dead cells. There are many different methods of removing these and they also have an effect on the flavor of the wine. Racking, where the clear wine is drawn off after the yeast has settled to the bottom is one. Some wines are deliberately left on the lees, the dead yeast cells, because this gives them a richness and depth of flavor – Champagne is a classic example of this and it is what gives the wine that delicious toasty aroma and taste. Muscadet Sur Lie is another example of this technique and you can taste the difference between the lighter wines that have been racked off and those that have not – it is quite astonishing. Most yeasts occur naturally and fermentation will start on its own, but sometimes if a wine maker is trying to create something quite specific a starter yeast may be used. However this can be fraught with dangers in terms of bringing in unnatural flavors such as the ‘Banana Beaujolais’ that was prevalent some years ago.


Botrytis or Noble Rot has a dramatic effect on the sugars in the grapes and consequently on the wines produced from grapes that have been affected by this benign fungus. It is prevalent in areas where there are large bodies of water that produce morning mists that are burnt off by afternoon sun. Day long mists produce gray rot which is altogether less pleasant. Sauternes, in Bordeaux is probably the best known area for botrytised wines. The grapes affected by botrytis are shriveled and look quite unpleasant but they produce the most fabulous sweet dessert wines. The fungus reduces the water content in the grapes making the sugars and the flavors far more highly concentrated. The grapes are generally hand picked at just the right stage which can involve as many as ten picking sessions to get the maximum amount of grapes at just the right point. The wines are generally aged for many years and have a rich, almost unctuous texture and flavor that is unique. The wines are highly prized and very expensive. They are not to everyone’s taste but I have to confess to a personal passion for them.

Without alcohol wine would not exist, it would merely be the juice of grapes. The amount of alcohol is dictated by the sugars in the grapes and the yeast used to ferment the juice. Wines from cooler climates often have less than 10% abv (alcohol by volume). The types of wine produced in warmer climates can have much higher percentages of alcohol, often dictated by the yeast used. There is a tendency for wines to be made with an abv of 14% or more, however the alcohol can completely overpower the wine itself and all you can taste is the alcohol ‘burn’, they should certainly not be drunk without food. The control of fermentation is where many winemakers display their skill, hot, rapid fermentation produces a very different wine to a cooler, more controlled process. If a winemaker wishes to protect the delicate fruit flavors of a wine such as Viognier, then temperatures must be carefully controlled or all its subtleties will be lost.

Of the external factors that affect the flavor of many types of wine, Oak is probably the most widely debated. Some wines are fermented in oak, or just stored in oak for a few months but it will always have an effect. Additionally the type of oak will produce completely different flavours. The effect of French Oak is harsher when young, emphasizing the tannins, but becomes buttery with age. American Oak is far more redolent of Vanilla and spice. Russian Oak is not dissimilar to French but is not yet as widely used. As well as the origin of the oak, there is the question of ‘old’ or ‘new’. Old oak barrels will impart some of the flavors of the previous wine and be mellower than new, some barrels are even ‘toasted’ to give yet a different set of flavors. Oak is not the only wood used for barrels, though it does have the most dramatic effect. One of my favorite wines, from Chateau Marie De Fou in the Vendee is aged in Acacia barrels and has truly unique and distinctive characteristics. The difference between oaked and unoaked wines is probably best demonstrated with Chardonnay – there are those that say it is dead without Oak and those who won’t touch it with Oak. It is very much a matter of personal preference.

All types of wine are affected by many things other than these basic internal and external components, and each will have a different effect depending on the type of grapes that have been used in the first place. Most of us start from either the grape variety or the region from which it came, but why not try following a more subtle thread in your choice of wine such as the difference between French and American Oak. These minute differences in types of wine can lead to some stunning discoveries and increase your enjoyment of the wines you drink.

About the Author: Brought up in a family of Wine Lovers Chloe Alster has a broad ranging interest in many types of wine, it’s cultivation, and history as well as the more social aspect of wine appreciation. Her views and opinions are well respected within the ranks of fellow enthusiasts. She writes extensively on Wine related topics at

Wine And Bottle

where you can read more about the components of wine mentioned in this article



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