Bar Tending For Science

Bar Tending For Science!!


I am not sure what provoked this latest event in my life, nor do I wish to seek professional counseling for this, but in May I decided to do something a little crazy.  I enrolled in a bar tending program and graduated 45 hours later – with honors!!  For over 2 weeks I spent an average of 5 hours a day learning and memorizing the techniques and content required to become a certified professional bar tender in the State of Nevada.  (Note:  There is no such thing as a certified bartender in Nevada – anyone can do this without attending school??).  Anyway, I paid the tuition and did the time!! 

The course consisted of learning proper technique in pouring, mixing, garnishing different drinks, safety in the workplace, health and sanitary requirements of the State of Nevada in food and beverage handling, legal liabilities of the industry, etc.  My final exam came in two parts; a written and performance exam.  The written exam was a 5 pager where I regurgitated laws, safety requirements, alcohol abuse signs etc. (I passed with a 100%!!).  The performance part of the exam entailed the instructor calling out 150 different drinks in ½ hour and we (the students) had to pour the drinks in the right order using the right glass, alcohol, and garnishes!!  I only missed 1 drink – that was the Shirley Temple – go figure that I would miss the only non-alcoholic drink on the test.  Even though I missed one drink I still had the highest score in the class – thus the honor – all my classmates had to buy me a drink after the final!!  (Note: There was no alcohol in the bar tending school – all of the different bottles of alcohol were filled with colored water – I know what fun is that!!).


SO – what is the science part of this bar tending venture???  People have been making and consuming beer and wine for well over 5,000 years, one source even speculates that this venture goes back to the Babylonian period as well as the Viking era at over 10,000 years ago.  However, we have only understood what we were doing for only the last century (MgGee, 1984).


If you were to look on the last page of Webster's New Universal Unabridged Dictionary (1983), you would find the word Zymurgy.  Zymurgy is defined as "the chemistry of fermentation, as applied in wine making, brewing etc." (p. 2129).  Zymurgy is the second to the last word in the dictionary.  The last word in this dictionary is Zythum, which is “a malt beverage brewed by ancient Egyptians” (p. 2129).  So there you have it – alcohol, (more specifically beer) gets the last word!!


Fermentation relates directly to the breakdown of complex molecules in organic compounds.  This breakdown is caused by the action of enzymes. This general definition includes virtually all chemical reactions of physiological importance, and scientists today often restrict the term to the action of specific enzymes, called ferments, produced by minute organisms such as molds, bacteria, and yeasts (Bamforth, 1998).


Some of the more common examples of fermentation are like the lactate bacteria that are naturally found in milk which turn the lactose into lactic acid and make milk go sour or "bad." Another example of fermentation is when butter becomes rancid and butyric acid is formed.  Another example is when wine turns to vinegar and forms acetic acid (Heaven forbid!!).


However, the Kingdom Fungi, provides us with one of the most famous fermenters.   Yeast is neither an animal nor a plant.  “Yeasts are now defined as a group of about 160 species of single celled, microscopic fungi.  Not all are useful: some cause spoilage of fruit and vegetables, some cause disease (for example, the fairly common “yeast infection” of Candida albicans).  Most of the yeasts used in making bread and alcoholic drinks are members of the genus Saccharomyces, or “sugar fungi.” (McGee, 1984, p.436)

Although yeast’s effects have been capitalized by humans since written records have been kept, and probably long before then, its true identity wasn't discovered until Louenhook invented the microscope and when Louis Pasteur found the bacterial rascals that had been plaguing the wine crops of France and then improved the process of wine making through a procedure now called pasteurization thus allowing yeast and only yeast to do the fermenting.  Actually there is quite a nice story there, but for another day!!

Yeast eats sugar ‑ so to speak.  Yeast is able to metabolize sugar (glucose) and break it down into ethanol with a natural by product of carbon dioxide.

C6H12O6 Þ   2C2H5OH        +              2CO2         + Energy

Glucose            Alcohol (Ethanol)          Carbon Dioxide


Essential to the yeasts’ production of alcohol is their ability to survive on very little oxygen, which most living cells use to burn fuel molecules for energy (remember the Krebs cycle!!).  No oxygen is needed to complete the energy transfer of glucose to ethanol and CO2 as shown in the equation above.  However, if this process is done in the presence of an abundance of oxygen the yeast cells convert the sugars completely to water and CO2. (McGee, 1984) (See equation below) Please note that no alcohol is made in this process thus explaining the reason we seal the bottles not only to capture the carbon dioxide, but also to end the redox cycle at the ethanol stage.


C6H12O6 + 6O2 Þ 6CO2 + 6H2O + Energy

Glucose + 6 Oxygen Þ 6 Carbon Dioxide + 6 Water + Energy           


Although this scientific knowledge was not known until the field of microbiology took hold in the mid 1830's, you can imagine one day when an early Babylonian harvested grain, then mashed the grain and mixed in with a little water in order to use it in a meal ‑ then was called away for a period of time.  Upon return the mash was found bubbling and giving off an interesting odor.  Not to be wasteful the mash was used in making what previously was very flat and uneventful bread, thus produced a light and fluffy, not to mention flavorful, bread that was very different than had been made before.  Although this is not a true story, one could imagine that since natural yeasts have been around longer than humans, it would be safe to say that when humans finally got around to being thinking and experimenting folk, yeast was discovered with all of its wonderful benefits.  It is said that the first real domesticated fermentation took place around 10,000 years ago when some honey was left or stored for a week or two and produced a beverage consumed in quantity by the Vikings.  Now perhaps, this same individual (Babylonian or Viking) who discovered the bread slurry or bubbling honey mixture also decided to drink some of the slurry after a period of time ‑ after a few slugs this person was feeling rather fine ‑ but different than anything felt before??  Thus the intoxicating influence of the ethanol that yeast converts the glucose to.  The rest is history ‑ so to speak!!  Grape skins naturally carry a yeast on them ‑ squeeze a few grapes and leave the juice for a while ‑ you get wine.  Even our avian friends enjoy the fermentation process ‑ just observe an American Robin Redbreast (Turdus migratorius) for a meal of ripened Pyrocantha berries ‑ at first it is just a social thing, squawking and a little feather ruffling ‑ then it gets serious when it is time to fly home and the intoxicating effects of the berries severely influence the birds ability to fly home ‑ designated flyers should be mandatory at each Pyrocantha bush!!


OK, we have now talked about the ethanol production, but how does that influence the body.  “Over the lips, past the gums, watch out stomach – here it comes!!).  Once alcohol (specifically, ethyl alcohol or ethanol) enters our body it begins to become absorbed almost immediately.  Ethanol is absorbed through the bloodstream via the gut.  “When a person consumes alcohol, the stomach and intestines rapidly absorb it. From there alcohol travels in the blood throughout the entire body, affecting nearly every tissue.  Moderate and high doses of alcohol depress the functions of the central nervous system, including the brain. The higher the alcohol level is in the blood, the greater the impairment” (  Alcohol is a drug that is classified as a Psychoactive substance.  “Psychoactive substances exert their effects by modifying biochemical or physiological processes in the brain. The message system of nerve cells, or neurons, relies on both electrical and chemical transmission. Neurons rarely touch each other; the microscopic gap between one neuron and the next, called the synapse, is bridged by chemicals called neuroregulators, or neurotransmitters. Psychoactive drugs act by altering neurotransmitter function” (  When the neurotransmitter function is altered, abilities such as hand-eye coordination, speech, sight, thinking, etc. all become impaired.  The effect of this impairment is known as inebriation.  “As blood passes through the liver, enzymes break down alcohol into harmless byproducts, which are eliminated from the body six to eight hours later. But the rate at which alcohol accumulates in the body may be faster than the rate at which the body eliminates it, resulting in rising alcohol levels in the blood.  Consequently, alcohol remains in the body, producing intoxicating effects hours after the last drink was swallowed” (  Most states have determined that the amount of alcohol in the blood that is sufficient enough to cause impairment that becomes dangerous to one’s self or others is .08%.  (Nevada is still holding out at .10%!!). 


The consumption of alcoholic beverages has undergone a great debate over the years as to the harmful or positive aspects of the activity.  The medical field agrees that excessive consumption of alcohol can lead to liver and heart problems and even death.  Some people become dependent upon alcohol resulting in a disease known as Alcoholism.  Alcoholism is debilitating to the consumer and the people associated with the consumer.  Other research states that a glass of alcohol (red wine) each day is good for the heart (American Medical Association).  And recent research (in TIME Magazine) stated that a stirred martini has more anti oxidents than a shaken Martini (Olive not included!!).  At any rate, alcohol consumed in small amounts tends to relax the consumer, relieve tension, increase appetite, and in some cases has no adverse effects at all.    However, when too much is consumed, the next day will result in a Hangover!! 


An article in the New Scientist (1997) entitled, “Drunk as a Skunk: Hangover research….” Explains the hangover process rather well.  “A small amount has no adverse effect and leaves completely raw.  We breathe out alcohol that reaches our lungs, and pee out any that arrives in the kidneys.  Most of it ends up in the Liver” (Coghlan, 1997, p.47).  When the ethanol reaches the liver it is time to go to work.  In the liver, “in cells called hepatocytes, enzymes go immediately to work.  First into the fray is alcohol dehydrogenase, which converts the ethanol into a more poisonous substance called acetaldehyde.  Fortunately, before this has a chance to do much damage, a second enzyme called aldehyde dehydrogenase wades in and converts the acetaldehyde into relatively harmless acetic acid.  This is then drained out of the liver and finds its way into the bladder” (p.47).  The hangover is thought to be caused by “a blockage of acetaldehyde waiting to be converted – particularly the queasy feeling and throbbing head” (p.47).  The rationale for this is explained through the drug Disulfiram or Antabuse.  “This drug is given to alcoholics which disables the aldehyde dehdrogenase, allowing acetaldehyde to build up . . . which results in headaches, vomiting, and a nausea so horrendous that even the most hardened alcoholic shies away from the bottle” (p. 47).


Another thought on the “Hangover” is from the build up of methanol, not ethanol, which all alcoholic drinks contain in varied, but small amounts.  Methanol is very poisonous to the human body as the breakdown (Similar in enzymic activity to the breakdown of ethanol) results in formic acid (Coghlan, 1997).  Finally, alcohol causes dehydration and depletes blood sugars in the body.  Such strategies as drinking a lot of water after an evening of imbibing and consuming sugars will help some of the effects of a hangover, but whatever you do – do not retreat to the “Hair of the Dog” as a hangover remedy.  For an evening of fun, retreat to the nearest neighborhood bar and ask the regulars what they do for a hangover!!


So, we come to an end.  We have spoken about the history, fermentation process, inebriation, and the hangover.  What remains is to serve a drink!!  And at that I will close this lengthy editorial, depart from my day job and retreat to my evening job at the Reno Hilton where you can find me standing behind the bar with a big smile waiting to serve you a drink!!  Enjoy and drive safe!!


Bamforth, C. (1997).  Beer: Tap into the art and science of brewing. Plenum Press, New York, NY.


Coghlan, A. (1997). Drunk as a skunk.  New Scientist, 20 (December 27th).


McGee, Harold (1984). On Food and Cooking; the Science and Lore of the Kitchen. Collier Books & Macmillan Publishing Co.  New York, NY.


Microsoft (2000). Encarta.  Available online at:  (



Selinger, Ben (1994) Chemistry in the Marketplace. 4th Edition. Harcourt Brace. Sydney, Australia.


Webster (1983). Webster's new universal unabridged dictionary (2nd Edition).  Simon & Schuster.    



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