The Perfect Cup of Coffee is Not Impossible to Make. Here’s the Science Behind it

Lifestyle | March 22, 2018, Thursday // 14:05|  views

There are few things better than the perfect cup of coffee.

Now, one scientist has made it his mission to discover exactly what makes the ideal brew. 

Dr Christopher Hendon, an assistant chemistry professor at the University of Oregon, claims the secret is in using the right type water alongside freshly-ground beans that have been stored in the fridge.

The scientist, also known as Dr Coffee, says caffeine-lovers should avoid drip-coffee pots and resist grinding their beans too finely as this may ruin the brew's flavour.

Dr Hendon says his study, which focused on espressos, stemmed from being puzzled about the inconsistencies in his drinks. 

As a result, he set out on a quest to make sure that each and every coffee he makes never varies from his winning formula. 

In a written statement, Dr Hendon said: 'One day you might have a good cup of coffee and the next day you might not.

'From a scientific perspective, it has always puzzled me why we couldn't do the same thing twice. 

'My research looks at every variable that goes into making espresso coffee, from grinding and packing the ground coffee, to water pressure and mineral chemistry.  


An assistant chemistry professor of chemistry from the University of Oregon called Dr Christopher Hendon used science to find out how to make the perfect cup of coffee every time. 

Known as 'Dr Coffee' in certain social circles, the caffeine-loving scholar looked at how certain things can affect the taste of coffee. 

1. Use hard water 

He found that hardness of water is related to better taste, the harder the water the stronger the taste.

Hard water is created by the presence of magnesium and calcium. 

These impurities help caffeine adhere better, which improves the taste and quality of the drink. 

2. Store the coffee beans in the fridge 

The research also revealed that the storage of coffee beans was very important for taste.

Fresh beans stored in the fridge came out on top here because freshly roasted coffee contains carbon dioxide that easily evaporates. 

As this evaporates, so does most of the flavour. 

3. Choose your grinder carefully  

The type of grinder used is also important, as if the beans are ground up too finely they can clump together, detracting from the flavour. 

A powder is desirable as it increases surface area, which in theory creates more flavour. 

This is a fine balance however, as ground too fine the coffee will become clumpy - detracting from the overall experience. 

4. Mix the coffee and the water evenly  

The final key to a good cup of coffee is the way the hot water mixes with the coffee.

This process should be consistent and steady for maximum taste.  

 'If every single café in America were to implement the procedure, it would save the U.S. 0 million (£214 million) a year by reducing the amount of coffee beans used to make espresso, while improving reproducibility.' 

Looking first at the water used, they concluded that 'hard' water with a high amount of magnesium and calcium causes coffee to have a stronger flavour than 'soft' water.

This is because compounds like caffeine stick to magnesium during the brewing process.

Hard water can also have high amounts of bicarbonate, which causes coffee to have a more bitter flavour.

They also confirmed that the storage of coffee beans was important for taste. 

Fresh beans stored in the fridge came out on top here because freshly roasted coffee contains carbon dioxide that easily evaporates. 

When these gases leave the beans, it produces a less flavourful cup of coffee.

Then they turned their attention to the grinding process. 

Dr Hendon said: 'There is a point in grinding coffee beans when you make too many small particles, which stick together and result in reduced extractions. 

'Although smaller particles mean a greater surface area, which should result in consistently tasty espresso, there is a critical point at which smaller isn't better.

'The grinders used can have a significant impact on the flavour of the resulting cup of coffee.' 


Caffeine has been deemed safe for consumption in doses of up to 400 mg per day for the general population. 

Studies suggest it can have a variety of health benefits, including combating liver disease and type two diabetes.

Research has even suggested it could even help people live longer.

It is the world's most widely consumed stimulant and reports show it can boost daily energy expenditure by around five per cent.

Researchers have said combining two to four daily coffees with regular exercise would be even more effective at keeping the weight off.

A 2015 study showed just a couple of cups a day could help millions of dieters stay trim once they have achieved their desired weight. 


Size of the ground beans was not the only factor to take into account when considering grinding.

To make a truly great cup of coffee, how the water comes into contact with the ground beans is crucial.  

Dr Hendon added: 'When extracting the espresso, the water should come into contact with the coffee grounds uniformly. 

'Passing water through the grounds in a systematic manner would ensure that all of the grounds come in contact with water equally. 

'In comparison, with a traditional drip-brew coffee pot, the water drips mainly through the centre of the grounds while the grounds on the outside have little contact with water.' 

 Using these revelations from his scientific process, Dr Hendon then put it into practice with a team of baristas.

They found that by altering the ground size and brew ratio they not only produced consistently good coffee but saved on the amount of beans used. 

He added: 'By predetermining the coffee-to-water ratio, as well as the water pressure, the maximum extraction can be systematically determined. 

'The barista can then iteratively improve their espresso reproducibility, while reducing waste coffee mass.' 

He has now turned his attention to improving the process even more by looking at grinding temperatures.

He has found that cooled coffee beans grind more uniformly and is working on the perfect ratios and ground size. 

Dr Hendon has presented his findings to the American Chemical Society.

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Tags: American Chemical Society, science, coffee, perfect cup, espresso, barista


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