Bubbly Beverages

The 17th-century mistake that put the ‘fizz’ into fizzy

The year was 1693, and a 19-year-old named Dom Pierre Perignon was put in charge of the extensive wine-making, then being carried out by the Abbey of Hautvillers in Northeastern France. Legend has it that this is where sparkling wine was discovered for the first time — and it was in fact an accident.

It’s said that, when Dom Pierre Perignon finally tasted one of his bubbly concoctions, he exclaimed “I’m drinking the stars!”

From sparkling wine to soda pop, bubbly drinks are hard to resist. Carbon dioxide bubbling out of the drink results in a tingling sensation in the mouth and throat. Many of us crave these fizzy concoctions, but did you ever wonder how these tiny bubbles even got trapped in these drinks?

The funny thing is, Perignon was actually tasked with preventing the wine from becoming sparkling [2]. It was unknown then, but the cause of all this trouble was the cold winters. At low temperatures, yeast enters a hibernation-esque phase. And the monks, assuming the fermentation to have ended, would bottle, cork, and bring the wine down into the storage cellar.

When spring emerged with warmer times, the yeast would suddenly awaken. They would begin metabolizing sugar again, producing a surge of carbon dioxide that led to higher and higher pressures being built up in the glass bottles.

Eventually, as you might expect, the bottles would explode.

This was all too common an occurrence, with either the cork ejected from the bottle or the glass shattering. And once one bottle exploded, it all too often led to a chain reaction with glass and corks and wine flying everywhere. To protect themselves from injury, cellar workers would often wear protective masks.

But in spite of the potentially dangerous circumstances, a period of great appreciation for the fizzy had just begun.

Sparkling wine includes any type of wine that is bubbly. This covers everything from Champagne to Cava to Prosecco. In fact, the only way these three sparkling wines differ is by the country they were produced in. Champagne is the most popular sparkling wine and legally must be made within the Champagne wine-making district in Northeastern France. Similarly, Cava is produced in Spain and Prosecco in Italy.

This means that the type of grape may be different, but the process of turning the wine into a sparkling, bubbly concoction is much the same, regardless of where the wines originated.

The key to creating those tiny bubbles within the wine relies on secondary fermentation, which begs the question: what is primary fermentation?

During the first fermentation, the juice from the grapes is placed in large, open vats. With the addition of the yeast, Saccharomyces cerevisiae, the fermentation begins. The yeast eats up the sugars in the juice and produces ethanol and carbon-dioxide (CO₂). Since the vats are open, any carbon dioxide is actually lost to the air. The first fermentation is only important for increasing the alcohol content to about 11% [2].

The second fermentation is where the magic happens. The wine has been sealed into a glass bottle with a cork, so this time, when the yeast creates carbon dioxide, it has no place to escape.

The CO₂ continues to be produced and entrapped within the wine. At this point, most of CO₂ is dissolved in the wine or in the liquid phase. Only a small percent is actually gas bubbles.

And as this CO₂ is produced, the pressure within the bottle gradually increases. By the time the yeast are done, the cork is holding each bottle under about six atmospheres of pressure. That’s about the same as being under 50 meters of water [3].

The high pressure within the bottle is exactly why the cork goes flying off the bottle as you open the sparkling wine. The pressure release also spurs the dissolved CO₂ to enter the gas phase, forming those tiny bubbles.

And that pop you hear is the high pressure finally being released.

Saccharomyces cerevisiae is also known as baker’s yeast, since it’s so commonly used in bread making. Like the other ingredients, the yeast is added to the dough, which is then usually rolled into a ball and left out at room temperature overnight. This time allows the yeast to rehydrate and start doing its work.

Professional bakers usually have a ‘proofing cabinet’ that holds the dough at 80–90°F, which is optimized for the yeast’s activity. Most amateur bakers who just let the dough sit out in the kitchen find that the yeast can work just fine at lower temperatures, around 65–70°F.

During proofing, the volume of the dough can double as the yeast produces carbon dioxide, which forms pockets within the dough. At this time, the gas pockets are pretty small, but once the dough is put in the oven, the heat results in all the gas cells expanding, often called oven spring.

The proofing step is named quite literally as it proves that Saccharomyces cerevisiae has been at work. Clearly, a yeast that is multi-purpose when it comes to making food and drinks.

The second way to get the “fizzy” into fizzy drinks is using artificial carbonation, which is largely credited to the Englishman Joseph Priestley.

It’s rumoured that in the mid-1700s Priestly suspended a bowl of water above fermenting beer. Some of the carbon dioxide that was being produced in the beer ended up being dissolved in the water giving it a slight carbonation [4]. At the time, Priestley didn’t understand it was carbon dioxide lending the effervescence to the soda water. Instead, he cited “fixed air” impregnating water to give it the bubbliness.

Priestley, of course, wanted to find an easier way than suspending water over fermenting vats of beer to result in carbonation. He found success in chemical carbonation when he mixed sulphuric acid with chalk (calcium carbonate), which did produce carbon dioxide gas. If the gas was directed into vessel of agitating water, the result was carbonation [5].

As you may have noticed, there was a little bit of a safety issue with Priestley’s new method. Sulphuric acid is an extremely strong reagent that can burn through skin and other materials. Not to mention, the reaction resulted in acid vapours that could be inhaled by the worker. These drawbacks help explain why Priestley’s process was never commercialized, but with time, other scientists would optimize artificial carbonation leading to the popularization of bubbly drinks.

Another scientist by the name of Johann Jacob Scheppe, a name still printed on cans of ginger ale and seltzer, helped to modernize artificial carbonation by studying how it was affected by temperature and pressure. This new approach on carbonation would rid the process of sulphuric acid, which was Priestley’s main downfall.

Using his own hand cranked compression pump, Schweppe saw that more carbon dioxide could be dissolved in water under high pressures. He also noted the importance of cold temperatures, which also seemed to aid more CO₂ to dissolve [7]. What he realised was that carbonated water could be held stably if it was in a pressurized container, and that it would only would release bubbles once the pressure was released. This is exactly what happens when you pop open a soda can: release the pressure, and you’ll immediately see bubbles emerge to the surface.

The same principles of pressure and temperature are still exploited in any soda machine seen in fast food restaurants or soda guns used behind bars. If you could see the inner workings, there would be a pressurized container holding CO₂ and booster pumps that increase the pressure of the water reservoir.

The bubbly water could be made in two ways. Either the pumps increase the pressure of water to allow plenty of CO₂ to dissolve or the equipment is capable of cooling water to a temperature that enables more CO₂ to be dispersed in the water.

That bubbly water is then mixed with flavouring syrup to make the drink Pepsi, Sprite, or Dr. Pepper, but each soda ultimately starts from the same source of carbonated water. Only at the last moment is a syrupy mixture of flavor and sugar added to distinguish each type of drink.

The science of carbonation may have begun with uncontrollable yeast and corrosive sulphuric acid, but with a little bit of experimentation, the field moved steadily forward.

Whether natural or artificial carbonation is used, the result is a delightful, bubbly beverage that kids and adults find hard to resist. Remember, this all started in a monk’s cellar full of exploding wine bottles and has somehow become one of the most popular ways to drink beverages.

And that, is progress in science!