Why Red Wine should always be allowed to breathe before drinking—this is what happens inside the bottle and the glass

When it comes to drinking red wine, it is often said to be an art, which begins with swirling the glass, pouring it into a decanter before serving, or letting the wine breathe. While this may sound like a ritual reserved for sommeliers, there's real science behind this common wine practice. According to wine experts, allowing red wine to breathe means exposing it to oxygen for a short period before drinking. But what exactly happens when wine contacts air? Here's a closer look at the science.

According to wine experts, when a bottle of red wine is opened, it begins interacting with oxygen in the air. This process is called aeration, which triggers a series of chemical reactions that can alter the wine's aroma and flavour. Once the bottle is opened, oxygen starts reacting with compounds such as tannins, phenols, and volatile aroma molecules. These changes don't happen instantly but gradually, improving the wine's sensory characteristics over several minutes to an hour.

If experts are to be believed, one of the biggest changes involves tannins, natural compounds found in grape skins, seeds, and oak barrels. Tannins give red wine its characteristic dryness and structure. It is proven that young red wines often contain firm and bold tannins that can make the wine taste bitter. And exposure to oxygen helps these tannins polymerize, or bind together into larger molecules. This is why many full-bodied wines such as Cabernet Sauvignon, Syrah, or Nebbiolo often benefit from being allowed to breathe.

According to wine experts, freshly opened wine might smell closed at the beginning, but as oxygen interacts with the wine and volatile aroma molecules evaporate, more complex scents become noticeable. Also, swirling the wine in the glass increases the surface area exposed to air, helping these aromas develop even further.

While it is a fact that red wines benefit from breathing, the required time depends on the wine's style and age. If we go by the experts, young tannic wines usually improve with 30 to 60 minutes of aeration. Older wines, on the other hand, are often more delicate, as they have already undergone years of slow oxygen exposure through the cork during aging. Hence, leaving them exposed to air for a longer duration is not a good idea.

It has been found that in some wines, particularly younger bottles initially, subtle sulfur-like or "reductive" aromas are released, which can resemble burnt rubber, struck matches, or boiled eggs. And these smells are caused by volatile sulfur compounds that occasionally develop during winemaking. Brief exposure to oxygen allows many of these compounds to dissipate, improving the wine's aroma.

It is important to understand that simply removing the cork allows a small amount of oxygen to enter the bottle. However, decanting—where wine is poured into a wide-bottomed decanter—increases contact with air and often produces noticeable improvements.

Yes, while moderate oxygen exposure improves the taste, excessive aeration can lead to oxidation. Overexposure makes the wine taste flat, dull, and overly acidic.