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Sugars in wine

Sugars in wine: “

Agne27: /* Fructose */ expand

The ”'[[sugar]]s in [[wine]]”’ [[grape]]s are what make [[winemaking]] possible. During the process of [[fermentation (wine)|fermentation]], sugars are broken down and converted by [[yeast]]s into [[ethanol]] alcohol and [[carbon dioxide]]. Grapes accumulate sugars as they grow on the [[grapevine]] through the [[translocation]] of [[sucrose]] molecules that are produced by [[photosynthesis]] from the leaves. During ripening the sucrose molecules are [[hydrolyzed]] (inverted) by the enzyme [[invertase]] into [[glucose]] and [[fructose]]. By the the time of [[harvest (wine)|harvest]], between 15-25% of the grape will be composed of simple sugars. Both glucose and fructose are six [[carbon]] sugars but three, four, five and seven carbon sugars are also present in the grape. Not all sugars are fermentable with sugars like the five carbon [[arabinose]], [[rhamnose]] and [[xylose]] still being present in the wine after fermentation. For this reason, no wine is ever fermented completely ‘[[dry (wine)|dry]]’ (meaning with out any [[residual sugar]]). Sugar’s role in dictating the final [[alcohol content]] of the wine (and such its resulting [[body (wine)|body]] and mouthfeel) will encourage winemakers to sometimes add sugar (usually sucrose) during winemaking in a process known as [[chaptalization]] in order to boost the alcohol content.<ref name=’Oxford pg 665-666′> J. Robinson (ed) ”’The Oxford Companion to Wine”’ Third Edition pg 665-666 Oxford University Press 2006 ISBN 0198609906 </ref>

Glucose, along with fructose, is one of the primarily sugars found in wine grapes. In wine, glucose taste less sweet than fructose. It is a six-carbon atom sugar derived from the breakdown of sucrose. At the beginning of the [[annual cycle of grapevines|ripening stage]] there is usually more glucose than fructose present in the grape (as much as five times more) but the rapid development of fructose evens the ratio out to where at [[harvest (wine)|harvest]] there is generally equal amounts. Grapes that are over ripe, such as some [[late harvest wine]]s, may have more fructose than glucose. During fermentation, yeast break down and convert glucose first. The linking of glucose molecules with [[aglycone]], in a process that creates [[glycosides]], also plays a role in the resulting flavor of the wine due to their relation and interactions with [[phenolic]] compounds like [[anthocyanins]] and [[terpenoid]]s.<ref name=’Oxford pg 317′> J. Robinson (ed) ”’The Oxford Companion to Wine”’ Third Edition pg 317 Oxford University Press 2006 ISBN 0198609906 </ref>

Fructose, along with glucose, is one of the principle sugars involved in the creation of wine. At time of harvest, there is usually an equal amount of glucose and fructose molecule in the grape-though as the grape [[ripeness (grape)|over ripens]] the level of fructose will be higher. In wine, fructose can taste nearly twice as sweet as glucose and is a key component in the creation of sweet [[dessert wines]]. During fermentation, glucose is consumed first by the yeast and converted into alcohol. A winemaker that chooses to halt fermentation (either by temperature control or the addition of [[brandy]] spirits in the process of [[fortified wine|fortification]]) will be left with a wine that is high in fructose and notable residual sugars. The technique of ”[[s├╝ssreserve]]”, where unferemented grape must is added after the wine’s fermentation is complete, will result in a wine that taste less sweet than a wine whose fermentation was halted. This is because the unferemented grape must will still have roughly equal parts of fructose and the less sweet tasting glucose. Similarly, the process of chaptalization where sucrose (which is one part glucose and one part fructose) is added will usually not increase the sweetness level of the wine.<ref name=’Oxford pg 290′> J. Robinson (ed) ”’The Oxford Companion to Wine”’ Third Edition pg 290 Oxford University Press 2006 ISBN 0198609906 </ref>

==In wine tasting==
{{See also|Sweetness in wine}}
In [[wine tasting]], humans are least sensitive to the the taste [[sweetness]] (in contrast to sensitivity to [[bitterness]] or [[sour]]ness) with the majority of the population being able to detect sugar or ‘sweetness’ in wines between 1% and 2.5% residual sugar. Additionally, other components of wine such as [[acidity]] and [[tannin]]s can mask the perception of sugar in the wine.<ref name=’Oxford pg 665-666’/>


[[Category:Oenology| ]]
[[Category:Sugar| ]]

(Via Wikipedia – New pages [en].)

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