How much do you know about alcohol? [Becky]

A few months ago I did a Science Showoff on alcohol – this is my expanded version of it including some of the things I learned along the way. Enjoy!

Everyone has a relationship with alcohol – whether you’re a regular at your local pub, or you abstain completely. Alcohol is deeply embedded in our culture and lives, to the extent that we probably couldn’t ban it if we tried, despite the health warnings.

But I’m not here to talk about the dangers. For a while now I have been fascinated by the science and history of it all. When did we begin drinking alcohol? How did we figure out how to make it? What actually is a hangover?

So many questions. How much do you know about this liquid you are merrily chugging down?

The Science

You are currently sitting in a broth of micro-organisms waiting to pounce. One of these is a fungus called yeast that sits and waits until a sugary, moist environment becomes available. Apples for example, while hanging on the tree, have a skin that yeast doesn’t invade, but as the fruit gets older the skin softens and the yeast come out to play.

A yeast called Saccharomyces cerevisiae, otherwise known as baker's yeast. Each numbered tick is 11 microns apart.
A yeast called Saccharomyces cerevisiae, otherwise known as baker’s yeast. Each numbered tick is 11 microns apart.

Through anaerobic respiration, a form of respiration that doesn’t use oxygen, the yeast convert this sugary goodness to energy. This process can also be referred to as fermentation, and it just so happens that a by-product of this is alcohol (plus some carbon dioxide).

So alcohol is really a waste product of yeast. Lovely. You can ferment pretty much anything as long as it has naturally occurring sugars, which is why we can ferment grain. Grain contains a hardy outer shell, so we need to allow it to get damp in order to soften the shell and make way for the yeast. That’s why we have to harvest the grain and store it in barrels in damp places in order to ferment.

This basic fermentation process accounts for our beer, cider and wine. But you can then distil the products of fermentation to make spirits.

The History

No one knows for sure exactly when we starting brewing, but the earliest written accounts go way back to Ancient times. It crops up in a few places, for example beer was an integral part of the Egyptian culture – we know this because of papyrus depicting their use of it. For them though, it wasn’t just about getting hammered; the Papyrus Ebers contains around 600 remedies for different illnesses, for which 118 were prescribed beer (they even used beer for enemas..). Alcohol was held in great esteem – the Egyptians believed that the deceased would need it for the long road to the afterlife, so not only did they put some in the tomb, but they also poured some into the corpse’s mouth.

The Egyptians were by no means the first and only people carrying out fermentation; they were just more meticulous about documenting it. Chemical analyses on bits of pottery from China have provided evidence that they were producing a concoction of fermented rice, honey and fruit as far back as 7000 BC, whether deliberately or not.

For beer at least, the basic recipe (yeast, grain, water + flavourings of choice) has remained relatively unchanged, although one major later addition was that of hops. In the Middle Ages, beer was a popular alternative to water as at the time it was much cleaner, having been boiled as part of the brewing process. That’s not to say everyone spent the whole time plastered – after the first strong brew had been made, the grain was recycled to produce a much weaker second brew; this “small beer” would be for general consumption.

But one major problem was stopping the beer from going off. Over time, the monasteries took up large scale brewing, and it was the monks who discovered that the hop plant provided a great, bitter flavour and a nice aroma. But crucially, they also discovered that it preserved the beer. Hops contain compounds that have antibacterial properties – for those of you that are interested, they have bacteriostatic properties meaning that it halts bacterial reproduction rather than killing them.

The hop plant, part of the same family as the nettle and cannabis.
The hop plant, part of the same family as the nettle and cannabis.

Clearly, basic fermented beverages were not enough, as we eventually figured out how to make things even more alcoholic. The first published book that refers to distillation as a method of concentrating alcohol appeared in the 1500s, although there is some evidence that it was being used as early as the 12th century.

If you’re interested in reading more about the history of alcohol, in particular beer, then I’d recommend Pete Brown’s “A Man Walks into a Pub – a Sociable History of Beer”. Very entertaining and informative.

The actual difference between lager and ale

Lager brewing uses a different type of yeast to ale. Despite the different types being very similar genetically, they behave quite differently.

Sugary galls on beech trees in South America that house Saccharomyces eubayanus, the yeast strain thought to have combined with ale yeast to form lager yeast. Click for source.
Sugary galls on beech trees in South America that house Saccharomyces eubayanus, the yeast strain thought to have combined with ale yeast to form lager yeast. Click for source.

Lager yeast (scientific name Saccharomyces pastorianus, or Saccharomyces carlsbergensis..I kid you not) is weird in that it works best at quite cool temperatures that would make ale yeast go to sleep. However, the fermentation does take a bit longer as these cooler temperatures, which is what led to it being called “lager” in the first place, meaning “storage” in German. What’s interesting is that whereas ale yeast is what we call diploid – i.e. it carries two copies of its genome in each cell, like we do – lager yeast is tetraploid, meaning it carries a whopping four copies of its genome around. However, this is made up of genomes from two different yeasts, making it a hybrid.

Why on earth would you have yeast that works at cold temperatures? It seems odd, but recently researchers discovered that lager yeast is a hybrid of our ale yeast, and yeast that thrives in cold temperatures from Patagonia in Argentina. The theory is that trans-Atlantic trade provided an opportunity for stowaway yeast.

What causes the hangover…

A lot of us have been there, a fair few times. Science might be the last thing you want to think about with a hangover, but I can’t help but wonder what is actually going on in my body. I guess that’s a Biochemist’s curse…?

Alcohol has a lot of strange and wonderful effects on the body, but there are a couple of main things that can really mess you up the next day:

  • Alcohol messes with your hormones. It puts the brakes on the production of a hormone called vasopressin, which looks after the body’s retention of water. When there’s less vasopressin around, water is sent directly to the bladder from the kidneys instead of allowing it to be absorbed back into the body (cue breaking the seal).

Your organs then try to make up for the water loss by trying to absorb more, but this means that your brain gets less water, meaning it decreases in size, tugging on membranes that connect your brain to your skull, resulting in the PAIN.

Going to the loo a lot causes you to get rid of useful salts like sodium and potassium too – the combination of this with losing the water results in the fuzzy headache, nausea and lack of co-ordination.

  • A lot of the hangover symptoms are brought on by acetaldehyde – this is a product of alcohol breakdown in the liver. Ironically, acetaldehyde is actually more toxic than alcohol itself, but luckily for us our livers also have an enzyme called acetaldehyde dehydrogenase, and glutathione, which together convert the acetaldehyde into something much less toxic. Unfortunately, we can run out of glutathione when we consume large amounts of alcohol in rapid succession, meaning acetaldehyde sticks around for a bit longer until more glutathione can be regenerated.
  • Congeners – these are chemicals that are either by-products of the fermentation process, or substances that are added later to give a certain taste, colour or smell. Certain drinks contain over 800 different congeners. Each alcoholic beverage will contain a different set and/or quantity of them, which is thought to be the reason why hangovers can be different depending on what you’ve been drinking, and in what combinations. *Supposedly* the greatest amounts of these are found in things like red wine, and dark spirits like whiskey and tequila, and less so in clear spirits such as vodka and gin.. Another consequence of the differences in congeners is that forensic analysts can not only figure out if you were over the blood alcohol limit, but in some cases can tell what it is that you’ve been drinking.

And as for how to cure the hangover, well; there are a fair few myths out there. Unfortunately, one of the only ones we know works is time. Many other “cures” either delay the inevitable, mask the symptoms, or just don’t do that much good at all. Doing research on the subject is very entertaining though – for example there have been studies carried out on artichoke extract (although it was only carried out on 15 people and the results showed it not to be effective, thank god..).

Right. To the pub!product_thumb

Sources and Resources

“A Man Walks into a Pub – A Sociable History of Beer” by Pete Brown.

A review on congener analysis for forensics (also has a table with the amount of congeners in certain beverages.

All other sources are linked to in text.


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