HOW Wine tastes sweet despite no added sugar

It may be obvious but sweetness is a perception – and also subjective. A common guess would be that the sugar present in the grapes causes this however sometimes that’s not the case. At this point of the conversation, we have some new information to share.
The sweetness in wine is mostly a characteristic determined by the winemaker’s style. Some actually add some form of sugar while fermenting it, which can result in sweeter wines, so there is absolutely nothing wrong with it. This method of adding sugar while fermenting is called ‘Chaptalization’ and is used to increase the total alcohol level of the wine when using underripe grapes. This method is commonly opted in France and Germany.
If your wine smells sweet or fruity at low levels, it actually denotes a fault called “Volatile Acidity”, which happens when the wine is oxidized along with microbial spoilage such as ‘Acetobacter’.

from a technical standpoint, the higher the acidity the less amount sugar would be in it, leading to residual sugar.
During the winemaking process, the yeast used for fermenting wine typically converts all the sugar into alcohol which leads to a dry wine. However, during the fermentation process, sometimes all the sugar is not fermented leading to some leftover sweetness in the wine.
Measured in grams per litre, it is the natural grape sugar leftover in a wine that is obtained after the alcohol fermentation process. It can vary from wine to wine and goes unnoticeable while buying.
Typically, the wines that have no sugar in them are technically called ‘dry wine’, however, the next time you get your favourite pinot noir, look for details at the back of the bottle and you will see that there is about 8-10 gms of RS/litre in it. But, if you look at the sweeter wines, the RS can go from 35-120 gms per litre.
Now you have learned a little bit more about wine and the sugar that’s inside it right?