Cracking open the mystery of how many BUBBLES are in a pint: Scientists reveal up to 1.5 MILLION tiny spheres can form in a gently poured lager
- French experts calculated the amount of carbon dioxide (CO2) bubbles in lager
- They measured imperfections in glasses that causes the CO2 bubbles to form
- Champagne is still the fizzier drink, however – according to their previous study
There’s up to 1.5 million bubbles in a glass of gently-poured lager, a new study reveals.
French scientists say their estimate is for a 250 ml (nearly a half-pint) glass of lager, which generally fizzes up more than ale.
The experts calculated the amount of carbon dioxide (CO2) bubbles in lager – which accounts for its creamy white froth – and imperfections in a glass that make the CO2 bubbles form.
Lager still doesn’t fizz up quite as much as champagne, however – research shows there are more bubbles in the sparkling wine than lager when comparing the same volume of both drinks.
After pouring beer into a glass, streams of little bubbles appear and start to rise, forming a foamy head. As the bubbles burst, they release carbon dioxide (CO2) gas, which gives the beverage a desirable tang as we take a gulp. As this image shows, 100 ml of champagne has 1 million bubbles; 250 ml of lager has up to 1.5 million bubbles. But this is dependent on tiny crevices in the glass that causes the bubbles to form (x axis)
The study has been conducted by Gérard Liger-Belair and Clara Cilindre, scientists at the University of Reims Champagne-Ardenne, France.
‘The number of bubbles likely to form in a glass of beer is the result of the fine interplay between dissolved CO2, tiny particles or glass imperfections acting as bubble nucleation sites and ascending bubble dynamics,’ they say.
ALE OR LAGER?
Beers are generally made out of four ingredients – grain, hops, water and yeast.
All beers can be classified as an ale or a lager.
Ales use top-fermenting yeasts – yeasts with cells that are carried to the top of the fermenting liquid.
Lagers use bottom-fermenting yeasts – yeast cells collect at the bottom of the fermenting liquid.
Bottom-fermenting yeasts work effectively at lower temperatures than top-fermenting yeasts.
Beer is prepared using four basic ingredients – water, malted cereal grains (such as barely or wheat), yeast and hops.
All beers, by definition, are either an ale or a lager, depending on what type of yeast they use.
Lager is the most widely consumed and commercially available style of beer, and generally tend to be light-gold in colour (although jet black lagers do exist).
Ales, meanwhile, include styles like stouts (including the world-famous Guinness), bitters and barely wines.
For their study, researchers focused on lagers, which tend to froth more when poured into a glass.
Lagers are produced through a cool fermentation process, converting the sugars in malted grains to alcohol and carbon dioxide (CO2).
During commercial packaging, more carbonation can be added to get a desired level of fizziness.
That’s why bottles and cans of beer hiss when opened and release micrometre-wide bubbles when poured.
These bubbles are important sensory elements of beer tasting, similar to sparkling wines, because they transport flavour and scent compounds.
Lager is the most widely consumed and commercially available style of beer – often favoured for its drinkability
When you open a bottle of beer, the sudden drop in pressure encourages dissolved CO2 to escape from the beer.
Most of this CO2 escapes in bubbles that form at the sides and bottom of a glass, where microscopic cracks and imperfections known as ‘nucleation sites’ serve as starting points for the gas to gather.
When the CO2 at a nucleation site reaches critical volume, a bubble detaches from the glass and launches itself toward the beer’s head.
For their study, the researchers first measured the amount of CO2 dissolved in Heineken, the commercial lager, just after pouring it into a glass.
Researchers tilted the glass as they poured, just like a waiter at a fancy beer bar would do to reduce its surface foam and make sure it doesn’t spill.
Two photographs from the research – a) shows the network of tiny crevices responsible for bubble ‘nucleation’ in glasses. b) shows a particle with a micrometric gas cavity trapped inside, acting as a bubble nucleation site in a glass poured with champagne
Using this CO2 value and a standard tasting temperature of 42°F (6°C), they calculated that dissolved gas would spontaneously aggregate to form streams of bubbles wherever crevices and cavities in the glass were more than 1.4 micrometre in width.
A single micrometre equates to one millionth of a metre, or one thousandth of a millimetre.
Then, high-speed photographs showed that the bubbles grew in volume as they floated to the surface, capturing and transporting additional dissolved gas to the air above the drink.
As the remaining CO2 gas concentration decreased, the bubbling would eventually cease and the drink would start to get flat.
CO2 bubbles grow in volume as they rise towards the surface. Here, high-speed photographs showing ascending and growing bubbles in a glass of beer (a), as compared with bubbles ascending and growing in a flute poured with champagne (b)
This image shows the number of CO2 bubbles likely to form in a glass poured with 250 ml of lager at 42°F (in blue) and a 100 ml glass of champagne at 50°F (in red). x-axis shows the size of cavities at the bottom of the glass that cause CO2 bubbles to form. 100 ml of champagne has 1 million bubbles; 250 ml of lager has around 1.5 million bubbles
There could be between 200,000 and 2 million bubbles ‘nucleated’ before a 250 ml glass of lager would go flat, the team estimate.
Professor Liger-Belair had previously determined that about 1 million bubbles form in a 100 ml flute of champagne, but they didn’t previously know the number created and released by beer before it turns flat.
‘In our previous study with champagne, we served only 100 ml (as usually done in champagne tasting,’ Professor Liger-Belair told MailOnline.
‘So, for a specific volume, the number of bubbles likely to form will be higher in champagne than in beer – mainly due to more dissolved CO2 in champagne than in beer.’
Surprisingly, defects in a glass will influence beer and champagne differently.
More bubbles form in beer compared with champagne when larger imperfections are present in the glass, the researchers also found.
Even though the study only used lager, this new estimation is likely to be a good maximum for beer as a whole (as ale tends to froth less).
The study has been published in the journal ACS Omega.
WHEN DID HUMANS START DRINKING BEER?
Humans have had a long history of consuming alcohol.
It is believed the primitive cultures of Mesopotania could have been brewing malted barley scraps as far back as 10,000BC but there are no records of it.
The earliest proof of beer-drinking dates back to Northern China 9,000 years ago.
This ancient brew was made using hawthorn fruit, Chinese wild grapes, rice and honey, and is the oldest known fermented beverage in history – older even than wine.
The earliest proof of beer-drinking dates back to Northern China 9,000 years ago
To make it the corn was milled and moistened in the maker’s mouth to convert starches in the corn into fermentable sugars – before it was ‘spat’ into the beer.
Throughout history, the consumption of alcohol may have helped people become more creative, advancing the development of language, art and religion.
This is because alcohol lowers inhibitions and makes people feel more spiritual.
It is believed the Egyptians started brewing beer around 5,000BC, according to the papyrus scrolls.
They were brewing things like dates, pomegranates and other indigenous herbs.
At around 3150 BC, the Egyptians used industrial-scale breweries to provide beer for the workers who built the pyramids of Giza.
Eventually beer made its way from the Middle East to Europe where an abundance of barley crops provided lots of raw ingredient for brewers.
Experts have now found evidence of brewing in Greece during the Bronze Age.
Researchers believe that these prehistoric people enjoyed getting merry with alcoholic drinks for feasts all year-round and not just when the grapes were ripe.
Not only was it considered nutritional it was also a safe alternative to drinking water.
It was in the Middle Ages that malted barley became the main source of fermented sugar and beer became the beverage we are familiar with today.
Source: Read Full Article
