I Saw the Science After A Pint

3 min read

“Another pint?” the barkeeper asked. It was 5pm on a Friday and my first glass of lager was almost empty. Yes, I confess, I was WFO (working-from-outside) at my favourite brewery, nursing a beer as I worked on my laptop. We’ve all been there.

Unlike my previous lager, my next beer, the seasonal Oktoberfest beer, was more amber in colour with a slightly different aromatic note. That was when I wondered, what made all the difference? 

Every beer ever made uses only 4 of the same ingredients: grain, hops, yeast, and water.


Grains can include wheat, barley, rye, rice, corn, oats, and other cereals. Most undergo malting at the start of the brewing process, where ripe grains soak in water and are then aired while constantly stirred. These grains germinate to produce enzymes and convert starch into sugars like fructose, sucrose, glucose, maltose, and maltotriose (in descending sweetness). Next, they are roasted to determine colour and taste. When roasted longer, grains become darker, sugars degrade, and the resulting beer is darker. It will also become less sweet and acquire a burnt bitter taste – thus the main difference between lagers and dunkels.


Hops are flowers from the hop plant. They act as surfactants – compounds that lower the surface tension of water so that molecules are more likely to interact with each other. It stabilises the brew so that we can taste the different bitter or sweet notes by clinging onto ions in the solution. It also contributes to the formation of beer foam. The more hops added, the bitterer it is.


This ingredient is what makes beer alcoholic and carbonated as it interacts with sugars to produce ethanol, carbon dioxide, and other by-products during fermentation. The ethanol may then react with organic acid present in the wort (the sweet liquid from malted grains) and form esters that give fruity flavours. For example, isoamyl acetate is known to give the banana-like flavour in Belgian and German wheat beers. Generally however, there are only 2 yeast strains.

Ale YeastLager Yeast
CharacteristicTop-fermenting (yeast rises to the surface; generates thick foamy layer)Bottom-fermenting (yeast stays in suspension; less foam; leaves sediments at the bottom)
Fermentation TemperatureWarmer (16-22°C)Colder (5-11°C)
FlavoursFruitier (due to esters) or spicier (due to phenols)Cleaner, crispier, and clearer (due to lower fermentation compounds in colder temperatures)


Beer is 90% water, so the quality of water makes a huge difference in the brewing process. It is also important to remember that water is different everywhere, with varying concentrations of magnesium, calcium, bicarbonates, and other ions. They can affect the growth of yeast, sugar metabolisation, and change in pH levels. The net pH levels would affect the perceived bitterness of the beer. 

In all, it’s impressive to think that these 4 ingredients can produce a wide variety of beer. Here are some profiles of different beer. Cheers!

Written by Lydia Yasmin
Illustrations by Lim Daphne


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