What makes a bottle of beer fizz over when it's been knocked or tapped by a mischievous friend/foe?
Most of us have been the victims of a bottle tap, which causes beer to foam over. Most people know that beer is carbonated -- the reason for the foam -- but why does a little tap set off the fountain of foam?
Most beers are supersaturated with carbon dioxide during packaging. Water (or beer) can only hold so much carbon dioxide, just like water can only hold so much sugar when making Kool-Aid. The higher the pressure, the more carbon dioxide the beer can hold.
This is seen when a package of beer is opened, some pressure is released and some CO2 creates a frothy head. The small tap on the bottle results in a sudden and short downward acceleration. The acceleration creates a pressure drop, allowing supersaturated carbon dioxide just enough time to come bursting out, thus causing the foam over.
Now why doesn't the jokester's bottle overflow? The bottle that hits the top of your bottle experiences a sudden deceleration creating a pressure increase, which actually stabilizes the carbon dioxide in that short time frame.
What is the deal with some cases and bottles requiring deposits? I thought Pennsylvania didn't have a bottle deposit law.
The life of more than 99 percent of American beer bottles consists of production in a glass plant, filling in the brewery, consumption and a final trip to either a landfill or a recycling plant. It was not always this way. One of the great advantages of glass was its ability to be reused and washed again. Breweries charged deposits on the cases and bottles as an incentive for customers to return the bottles and cases.
The brewery then washed and refilled them. This saved the energy expended in producing an entirely new bottle and case for the beer.
Today, few brewers continue this environmentally friendly process. A returnable bottle may last for decades and be filled more than a hundred times.
While the thought of reusing a beer bottle may seem odd, it is no different than drinking out of a glass at a restaurant. Would you toss your dishes in the garbage after each meal?
There is no need to worry about sanitation, as the bottles undergo a 30-minute hot caustic wash with steam that dissolves the label and thoroughly cleans the bottle. There is then a manual or automated inspection of the bottle to insure its fit for refill.
Thus rather than paying dollars for a new cases and bottles, there is a matter of only a few dimes to wash and reuse the containers.
This savings is passed onto the consumer as a case of returnable bottles usually sells for $2 to $3 less than non-returnable bottles of the same brand.
Most other countries take advantage of this system. Many Canadian brewers package in returnable bottles. In Germany the majority of bottles are returnable.
The practice is not limited to beer bottles as many sodas are packaged in returnable bottles in places like South America to lower the price of the beverage.
Americans have just become accustomed to one time use products and thus returnable packaging of all sorts has become a rarity.
Chris Straub is a senior majoring in chemical engineering and a Collegian columnist. He is also the great-great grandson of the founder of Straub beer. His e-mail address is cts150@psu.edu.
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A sign of a fresh and quality beer is a distinctive lace it leaves on a glass, often called Brussels lace due to its actual resemblance to the material.
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Although the main source of fermentable sugars in U.S. beers is malted barley, other less widely used starches include cassava root in Africa and potatoes in Brazil.
encycl.opentopia.com
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The tax on wine and spirits in Pennsylvania was enacted in 1936 to help rebuild Johnstown after the flood of 1889. It became known as the "Johnstown Flood" tax and amounts to more than $200 million yearly.
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