An Exploration of Tiny Bubbles: The Science Behind Nature’s Magic
Bubbles in Sparkling Wine are not just pretty, little nothings. They work harder than you think.
For one thing, they are not empty. The bubbles deliver hundreds of molecules to the top of the glass. When they explode on the surface, they deliver the aromas & flavors which make top quality Sparkling a truly delicious wine.
Creating bubbles is the littlest trick of nature. This begins at Iron Horse Vineyards by hand harvesting the fruit, gently pressing the grapes. We then ferment the juice completely dry, making a gorgeous blend and ultimately bottle it as a low alcohol base wine … adding a precise amount of sugar and yeast.
The sugar triggers the secondary fermentation, bumping up the alcohol by about a point. One of the natural by-products of fermentation is the creation of carbon dioxide (Co2), which normally escapes from the barrel or the tank, but for bubbly we trap it in the bottle with a crown cap, forcing the gas to dissolve into the wine creating … ta da … bubbles.
More than 600 chemical compounds join the carbon dioxide - each lending its own unique aroma and flavor quality.
The magic is in how long we age the wine on the yeast in the bottle. The longer we age it en tirage, the smaller the bubbles and the greater the finesse on the wine.
A perfect example is our 2000 Brut LD, aged for 14 years and disgorged just last month.
The yeast cells feed on the nutrients in the wine. As they become saturated, they start to die off giving back to the wine a rich, creamy texture through a chemical progress (autolysis), much like stirring the lees of Chardonnay in the barrel.
You can see the difference just holding the glass to the light. Big bubbles are called “frog's eyes”. Not a compliment!
You can also feel the difference. The longer the wine is aged on the yeast, the more integrated the bubbles, the smoother the texture, the more elegant the “mouth feel.”
As the yeast cells break down, they emit amino or fatty acids that coat the bubbles, so that when they launch off the bottom of your glass, they don’t glom together. Instead they stay separate and travel up to the surface in streams of tiny, diffuse, gas-filled spheres.
As the bubbles ascend the length of a glass in tiny trails, they drag along the molecules of aroma and flavors which explode out of the surface.
When they burst, they release enough energy to create tiny auditory shock waves; the fizzing sound is a chorus of hundreds of individual bubbles bursting every second.
With each sip, the bubbles excite special receptors on the tongue contributing to that tingling feeling that makes bubbly so seductive.
The bubbles also serve to retain the acidity of the wine. A flat bottle will taste too sweet and out of balance.
The collapse of bubbles at the surface is even more exciting under a microscope.
According to Gerard Liger-Belair, a physicist at the University of Reims in Champagne (of course), bubbles collapsing close to each other produce unexpected lovely flower-shaped structures unfortunately completely invisible to the naked eye.
“This is a fantastic example of the beauty hidden right under our nose.” (Source: Uncorked: The Science of Champagne, published by Princeton University Press.)
British physicist, oceanographer and Champagne aficionado Helen Czerski, explains that bubble dynamics of Sparkling Wine are the same as in the ocean, but with greater consequence. Bubbly can change our mood, but the bubbles in the ocean affect climate.
"Bubbles are little packets of gases that rise or fall as if they're on little conveyor belts," she says. They carry carbon dioxide and oxygen from the atmosphere down into the ocean, and then when they go back up again they pop and sulfur compounds from marine plants are sent upward, forming particles in the air that lead to the formation of clouds."
Czerski is studying how to detect and count ocean bubbles of different sizes to help scientists in other disciplines create more accurate models. She said that scientists have found it difficult to judge the effect of bubbles on their data for years and usually have had to add a "fudge factor" to account for them.
"For instance, bubbles ring like bells when they are formed or when sound waves go past them, and if you're studying sounds traveling through the ocean -- like sounds from whales or sonar -- bubbles can get in the way of what you're trying to listen for,"
And she adds, “A good way of getting people to enjoy my lectures on bubbles is to give them a glass of Champagne.”
Her favorite “parlor trick” is to drop a few raisins into the fizz. The raisins sink to the bottom of the glass, before being lifted back to the surface by the bubbles, which then burst, sending the raisins back down again.
So, what’s the best way to pour a glass of bubbly and maximize the sensory experience? A study published in the American Chemical Society Journal of Agriculture and Food Chemistry answers that question. Pouring on an angle preserves twice the carbon dioxide bubbles compared to pouring down the middle of the glass.
More scintillating sparkling facts:
Never underestimate the force of a flying cork. The warmer the bubbly, the more the pressure builds and the faster the cork flies when you pop it open, clocked at up to 30 mph.
The magnum is the optimum size for bubbly because the larger bottle retains more CO2 in the wine as it is being poured.
The white wisp of mist rising from a just-popped bottle is not carbon dioxide. That's a fog of ethanol and water vapor, triggered by the sudden drop in gas temperature when the pressure is released. (adiabatic expansion)
No need to swirl a glass of Bubbly, in fact it is frowned upon. The bubbles are already releasing the aromas and flavors. Swirling just knocks down the bubbles we work so hard to achieve.
Now let's talk about glassware.
The old fashioned flat coupe ( like the ones my parents drank from at their wedding) has a very slow bubble engine because the bubbles don't get to rise very far. Flavour is delivered to the air gradually, but escapes from the space above the glass very quickly.
The tall thin flute has a very powerful bubble engine, delivering lots of flavour very quickly, and spitting lots of fizz upwards.
Some sommeliers like to serve champagne in white wine glasses because flutes "stifle the flavour".
The Riedel glassmakers have taken it a step further with their new “Champagne Wine Glass.” President, CEO, & 11th generation glassmaker Maximilian Riedel says “the larger rim diameter enables the aromas of the Champagne to be released” and complexity to develop.
I had the honor of conducting an impromptu experiment with George Riedel, Maximilian’s father, several years ago in Healdsburg. We tasted Iron Horse vintage Blanc de Blancs side by side in a flute and a Burgundy glass. In the flute, the Bubbly was bright and vibrant. In the other glass, it seemed older, softer.
Next time, I hope to try it in a glass slipper.
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