Why does glass shape affect how wine smells and tastes?
The flavour may depend on the vessel you choose. Karl Kruszelnicki explains.
We humans have drunk alcohol for thousands of years and that means we’ve had plenty of time to make different shapes of glasses to drink alcohol from. We’ve got shot, brandy and martini glasses, and several different types of wine glasses.
Some rather recent and neat technology can show alcohol concentrations in the air in real time. These analyses seem to have confirmed that wine connoisseurs’ claims could well be right: the shape of the wine glass can affect the aroma and flavour.
Kohji Mitsubayashi and colleagues at Tokyo Medical and Dental University developed the technology. It can directly image, in real time, ethanol vapour escaping from a glass.
They started with a one-millimetre thick cotton mesh. It had tiny holes about one millimetre across, and measured 80 millimetres by 80 millimetres. They added a whole bunch of very specific chemicals, including one called “luminol” which glows when it detects ethanol. They then part-filled the test glasses with a Japanese red wine.
As the ethanol rose, it hit the cotton mesh. A bunch of chemical reactions started, and the luminol began to glow. By 50 seconds, the light output of the glowing cotton mesh had stabilised. They repeated the experiment with various glasses and at different temperatures.
The researchers found that ethanol vapour appeared in a very characteristic ring shape. Alcohol concentrations were low towards the centre, but high in a doughnut-shaped ring just inside the rim of the wine glass.
Because the alcohol concentration was lowest in the centre of the glass, that made it the best location to sample the most delicate aromas of the wine. Without the overpowering alcohol cloud, the other aromas could come forth and present themselves. The authors wrote: “The shape of the wine glass has a very sophisticated and functional design for tasting and enjoying the aroma of wine.”
Certainly, over the years, wine connoisseurs have maintained that the same wine can have very different bouquets and finishes depending on the wine’s temperature and the shape of the glass it’s served in.
For example, it’s been claimed that the tiny bumps present on the surface of lead crystal glass can bring forth a multitude of extra fragrances.
The wine scientist Régis Gougeon, from the University of Burgundy, France, admired the new technique, saying: “This work provides an unprecedented image of the claimed impact of glass geometry on the overall complex wine flavour perception, thus validating the search for optimum adequation between a glass and a wine.”
In other words, this new technique allows better matching of the wine to the glass in which you serve it.
But there are several things to note. The doughnut effect happened at 13 °C, but vanished at 17 °C. It was only observed in the wine glasses, and was most pronounced in a pinot noir glass.
Finally, in accordance with all known Ethics Committee Requirements, no wine was wasted in this study …
Credit: Edited extract from Short, Back and Science, Macmillan 2015.