A teaspoon in the neck of a bottle of champagne does not prevent the bubbles from escaping.
A TEASPOON PLACED IN THE NECK of a bottle of opened champagne, it is said, will help preserve its fizz for a certain time. Some even go so far as to claim that the effect occurs only with silver spoons. What reason is there to believe such dictums, which seem to be the product of nothing more than unscientific experimentation? By virtue of what strange physicochemical principle could a teaspoon trap the bubbles of this noble beverage of celebration? As it happens, there is no need for us to inquire into this matter ourselves because the Comité Interprofessionnel du Vin de Champagne has already carried out a rigorous series of experiments on the “teaspoon effect.” Their findings, which turned out to be negative, were initially published in the Vigneron champenois.
Michel Valade, Isabelle Tribaut-Sohier, and Frédéric Panoïotis had the advantage of being able to institute reliable controls that few of us have, particularly access to an ample supply of bottles of champagne from the same vintage, differing from one another as little as possible. To simulate consumption, the bottles were partly emptied, either by a third or by two-thirds. Some were left open; others were equipped with the famous teaspoon, silver or stainless steel depending on the case; still others were stopped with a cork; and a final batch was sealed by a metal crown cap. All the bottles were placed in an upright position at a temperature of 12°c (54°F). In order to test the quantity of residual gas, pressure, loss of weight, and taste were measured at regular intervals.
Pressure Variations
The pressure of the champagne at the outset was about 6 bars. As the bottles were emptied, the pressure fell to 4 bars when the residual volume was 50 centiliters (16.9 oz.) and to 2 bars when the volume was 25 centiliters (8.5 oz.). Subsequently, the drop in pressure was similar for all the bottles that had been left open, with or without a teaspoon; it was less for the bottles with caps (10%, instead of 50% in the case of bottles left open for forty-eight hours).
To forestall criticism of these preliminary measurements from skeptics attached to the myth of the teaspoon, the researchers also measured the loss of weight through degassing. Once again the weight loss was observed to be identical for the open bottles and for those whose neck was fitted with a teaspoon. By contrast, the loss was zero for the bottles that had been stopped with a cork. Although a little gas escapes from the liquid in this case, its accumulation on top of the liquid limits any further release; when the bottle is uncorked the next time for measurement, the noise of its being opened reveals the presence of this accumulated gas, but the quantity of dissolved gas remains greater because the cork stopper limits the degassing of the wine.
In Vino Veritas
These measurements confirmed that degassing depends chiefly on the pressure exerted downward on the liquid, the presence of suspended matter in it, and imperfections in the inner surface of the bottle. This last effect is clearly visible when one puts sand in a glass of champagne or when champagne is poured into a frosted glass: bubbles immediately form in great numbers, triggered by the irregularities introduced in the liquid.
Saving the best for last and for themselves, the Epernay researchers tasted the contents of the various opened bottles. This blind tasting confirmed that the teaspoon did nothing to preserve the sparkling character of the champagne. By contrast, the samples that had been preserved in hermetically sealed bottles were more effervescent. In every case the wines had oxidized because oxygen had been let in when the bottles were partly emptied. But never mind that cork stoppers preserve champagne better than teaspoons; one should not put off until tomorrow what one can do today. Once you’ve opened a bottle, finish it off!