Ah September, the leaves begin to change, light crisp air slowly starts to replace the heavy and humid conditions of August and students return to the campuses of this great country. And what will meet those students and their sponge-like brains? Well, certainly knowledge, camaraderie and experience to name a few, but there will also be beer — lots and lots of beer.
Since this is the science section of this fine paper, and there is quite a bit of science behind the brewing and metabolism of beer, why don’t we take some time to examine that amber liquid in some depth, from grain to brain, as it were?
At the heart of beer, and indeed all alcohol production is fermentation, a process by which microorganisms ingest sugar and convert it into chemical energy. The two primary byproducts of the fermentation used for alcohol production are ethanol — the scientific name for the kind of alcohol humans consume — and carbon dioxide.
One of the microorganisms commonly used for beer production is a yeast species called Saccharomyces cerevisiae, which roughly translates from Greek into “sugar mold of beer.” It is also the common yeast used for bread making, which, like beer production, relies on fermentation, only instead of alcohol bakers are interested in the carbon dioxide, which helps bread dough rise.
While brewers could use sucrose — table sugar — for fermentation, alcohol producers normally choose to use plants with high amounts of natural sugars to power their little fermenters. Not only is this cheaper than using refined sugar, but it also has the added benefit of providing flavour to the alcohol being produced. Beer producers traditionally use barley as a source of sugar; however before it can be used for beer production the barley has to go through a process called “malting.”
Those of you living with health-nuts or farm animals will be familiar with barley, or the seeds of the Hordeum vulgare plant. When harvested, barley is full of starch which is composed of long chains of the simple sugar glucose. While multicellular plants and animals can easily (sometimes too easily . . .) convert starch into sugar for energy, yeast cannot accomplish this as quickly. As such, barley used in beer production is put through a malting process, whereby the grain is soaked then stored, tricking the barley into thinking that it has been planted and triggering germination, which includes the conversion of the seeds starch reserves into maltose, a form of sugar, similar to sucrose. Under normal conditions, the resulting maltose from germination would give the barley’s genetic material the energy it needs to grow into a sprout and push its way out of the soil, however brewers take advantage of the abundance of sugar in the malted barley, and use it to fuel their fermentations.
In fermentation, S. cerevisiae uses enzymes to process the sugar in a pathway called glycolysis, which roughly translates to “break glucose.” The final product of this pathway in S. cerevisiae is energy, carbon dioxide and ethanol .
In beer production the ethanol provides the alcoholic content while the carbon dioxide from the reaction gives beer its distinctive bubbles. In some cases hops, the female flower of the hop plant, which is a bine—similar to a vine—that grows in temperate areas of the northern hemisphere, are added to the yeast and barely mixture, lending a bitter taste to the beer.
Once fermentation has completed the beer is filtered, removing the solids from the fermentation process. If more bubbles in the beer are desired yeast and sugar can be added during the bottling process.
As the yeast continues to turn sugar into ethanol and carbon dioxide the alcohol, concentration in the fermentation vessel will continue to rise, eventually reaching a point where it is toxic to the yeast. In the case of S.cerevisiae used in beer production around five per cent by volume — or 5 ml of ethanol in 95 ml of water — is toxic. But this number can go as high as 21 per cent with special yeast strains, such as those used in wine making.
Beverages with high percentages of ethanol by volume, such as whiskey and vodka, must be made using a process called distillation, where ethanol is boiled off from the fermenting liquid and collected. With each distillation the percentage of alcohol increases, however the compounds, which give the alcoholic beverages their flavour become increasingly rare each time the process is repeated. In the case of whiskey, little flavour and colour of the original fermentation remain following the distillation. It isn’t until the distillate, is aged in oak barrels that the beverage develops it’s characteristic golden colour and flavour.
Alcohol and you:
As anyone with a “crazy uncle” knows, excessive alcohol consumption leads to drunkenness. But what is drunkenness? What happens inside your body, and why do you feel the way you do?
The New Webber Dictionary defines the term “drunk” as being “Intoxicated; inebriated; overcome, stupefied or frenzied by alcoholic liquor.” And while this is a concise definition, it lacks scientific precision. Scientifically speaking, ethanol is a depressant of the central nervous system. The severity of the symptoms of alcohol intoxication is normally dependent of the blood-alcohol content (BAC), or the percentage of ethanol in one’s blood. In the province of Manitoba, a BAC of 0.05 per cent is considered too high to operate a motor vehicle, while a BAC of 0.40 per cent can be lethal.
The linings of your stomach and small intestine are highly vascularized, meaning that there is an abundance of tiny blood vessels, whose job it is to absorb and transport the sugars and nutrients of your food that are immediately available into the blood and throughout your body. Your digestive tract allows ethanol to move into the blood, where it gets transported to the brain. Once in the brain, ethanol interferes with neurotransmitters and synapses, which are associated with brain functions such as motor control, judgment, memory and inhibition, but these effects soon start to dissipate, since, to the adoration of beer lovers everywhere, the human body has a system in place for removing ethanol from the body.
Alcohol dehydrogenase, an enzyme present in the lining of the stomach and liver, breaks ethanol down into acetaldehyde, which is then converted into harmless acetic acid — also known as vinegar — by acetaldehyde dehydrogenase. Variations in the amount, and effectiveness of an individual’s dehydrogenases can be a factor in determining one’s tolerance for alcohol, and the severity of the hangover.
Hangovers, a result of drinking to intoxication, generally include headaches, body aches, sensitivity to sound and light, in addition to many other complaints. Unfortunately for hangover sufferers and pharmaceutical companies everywhere, scientists simply do not know what causes hangovers. Some believe that increased urination, caused by ethanol leads to dehydration, while others speculate that a deficit nutrients in your body, which are used up by dehydroginases as they convert ethanol into vinegar could lead to the symptoms experienced by hangover sufferers. More recently however, researchers have suggested that a hangover could be the result of alcohol withdrawal, experienced by your body as the ethanol slowly leaves your system.
Regardless of the cause, if you plan to drink, your best bet for avoiding a hangover is to drink in moderation. If this is not possible or desired, drinking lots of water and popping some vitamin C tablets has been shown to reduce the severity of hangovers.
So there it is, your comprehensive guide to alcohol. Hopefully your interest has been piqued, and you have found something to take away. At the very least you should have found some facts to impress your friends while doing a kegstand or popping a cork. Just remember, drink responsibly and may the force be with you.