A wine aerator is a small, in-bottle, hand-held pour-through or decanter top device for aerating wine. These devices mix air into the wine as it flows through or over, increasing exposure to oxygen and causing aeration. They offer an alternative to swirling, traditional decanting, and to aldouze (i.e. to wait for wine to breathe). This category emerged in the United States in or before 2007. This timing can be partially linked to the decline of the US economy which resulted in wineries releasing wine early to compensate for sales dips.
There are a number of styles of wine aerators and approaches to accomplish aeration. While injection-style hand-held acrylic aerators are currently most common, in-bottle and decanter top aerators are also available. Sieve-style decanter top funnels have long been used for aeration and catching sediment. Aerators are made from food safe-plastic or glass, and decanter top aerators are commonly stainless steel.
Injection-style aerators work by the Venturi effect, an application of Bernoulli's principle: they feature a wide tube that narrows. This effect is widely used in engineering applications, for example to mix air and fuel in carburetors. This method has been noted by wine experts to be too harsh for thinner skinned verietals such as Pinot noir or Gamay.
Boxed wine and vacuumed sealed wine can be aerated through the use of a single glass aerator. There are a number of different types of single glass aerators. Some have a movable spout that adjusts to the different size and shape of a wine glass.
Decanter-top aerators are the longest used and the most varied in design. Variations on the metal funnel are common, as are shapes and figures placed in the decanter neck. Pouring over the object creates agitation.