When I considered ‘posting’ my opinion in a blog on the internet, I felt that it was necessary to contribute thoughtfully to the greater discourse on the topic of my long-term interest… wine.
Recently, Rita and I attended a tutored tasting by a Riedel glass representative at the lovely new cellar door at Velo winery in Legana.
My mind-set was that a bigger glass with a narrow rim would simply show any wine better by combining a broad surface area to release aromatics with a constriction at the rim to trap or hold these aromatics. The nose of the wine would be enhanced but no change to the structure of the wine would be seen on the palate.
The presenter was confident and professional and demonstrated the benefits of the glasses on show, embellishing the bouquet of the wine in the appropriate glasses and pointing out the structural differences on the palate.
My scepticism regarding the shape of the glasses and the effect on the structure and balance of the wine was challenged as in some examples (not all), I was in agreement with the presenter.
How could this be? Especially the effect upon structure and balance that related to the acid, alcohol, phenolics/tannins and extract.
That night we experimented with a larger range of glasses and different red and white wines. Again there appeared to be glasses that suited particular wines by enhancing both bouquet and palate.
So after puzzling for some time over this conundrum, I offer these thoughts…
One variable need to be considered first and that is the volume poured as a standard pour of 150mL may be greater than or less than the most effective level in the glass, so let’s assume the pour is just short of the broadest point of the glass, which for most large format glasses is accommodating 150 mL.
We can now consider a number of features relating to the shape of the glass.
- The total glass capacity of enclosed air space above the wine.
- The broadness or diameter of the glass.
- The height of the glass from the wine surface to the rim.
- The rim diameter.
- The shape of the glass- simple spherical bowl or tulip shape with symmetry or varying tapers including reverse tapers at the rim.
There can be a threefold increase in surface area from a standard XL5 glass to a Riedel Chardonnay glass and this may approach a factor of 4 when the wine is swirled and the surface takes on a spherical shape.
Again comparing the volume of air space available to take up released aromatics, there is probably a tenfold increase from an XL5 glass to the Chardonnay glass. Even a deep sniff is unlikely to exhaust the volume of a large glass but would easily remove the volume of the airspace of the XL5.
The height of the air space above the wine surface can vary between 6 cm for an XL5 glass to 10 or more for the larger Riedel glasses.
Finally, the rim diameter may not seem to vary as dramatically between glasses but just a 1.5 cm difference between a Riedel Chardonnay glass and the Pinot glass results in a 50% increase in surface area at the rim.
I can see how the surface area of the wine will affect the perception of the bouquet as the movement of volatile compounds into the air space will be proportional to the surface area. The ‘enclosing’ of the airspace will be important to trap these volatiles.
I did notice the difference between the Riedel Chardonnay glass(simple bowl) and the Riedel Pinot noir glass which was more subtle than just intensity. I suspect that the greater height of the airspace of the Pinot glass could allow for some ‘stratification’ of the volatiles released where some compounds move faster to the rim. These molecules may represent ‘lighter’,fruitier notes of the bouquet. This may be independent to the molecular weight of the volatiles.
The average inspiration volume of a deep ‘sniff’ of a wine is unlikely to exhaust the capacity of the airspace of a large glass so that the air sampled by sniffing at the rim would be different to the air directly above the surface of the wine.
But where could the perceived structural differences for both red and white wines between the wineglasses come from?
Surely transferring the wine from a glass to the mouth should eliminate variability as the mouth becomes the final container of the wine.
If we consider the surface of the wine as the liquid/air interface then a number of physical and chemical processes will be happening.
Free sulphur dioxide will be being lost, volatiles will be moving out of this surface layer at different rates and oxidation of some compounds will occur.
Sipping will ‘sample’ this surface layer as wine will flow from a glass in a near laminar movement and a broad glass of say 10cm. diameter will deliver 7.5 mLs. per 1 mm of surface depth (close to a ‘conservative’ sip!)
Structure of both red and white wines is dependent on the interplay of acids, phenolics/tannins, residual sugar, alcohol, extract and perceived fruit intensity when the wine reacts with saliva.
Although the acids, extract and residual sugar are unlikely to change with short term exposure to air in the surface layer changes to phenolics, alcohol and perceived fruit intensity and character will influence the perception of the balance between all the structural components.
Finally although I have seen a proposal that the rim diameter governs the flow rate from the glass and therefore changes the position on the tongue that the wine first hits as the head tilts back to create the ideal flow, I agree with others who suggest that the wine will be immediately ‘massaged’ around the mouth allowing a full range of taste buds on the tongue to be stimulated in the briefest of time.
In summary then I am convinced that different glass shapes enhance the experience of the different varieties and supports the efforts of companies like Riedel to accommodate as many variations in their range.
But only by personal experimentation can the myriad varieties, blends, styles and bottle age be matched to a glass design to find the ideal glass for that particular bottle of wine.