The science of a perfect cuppa.

Britain is a nation of tea lovers. We are obsessed with it for some reason. Although tea originates from Asia, Britain have reclaimed (along with many other things) the hot beverage that is a cuppa. I myself, have at least three cups of tea a day when I’m at home. I never buy a tea when I’m out because they just don’t taste the same! So why do they taste different? And how can I make the best cup of tea ever? 

Photo Credit: RHS. This is the Camellia Sinesis plant, where black and green tea originate from.

Tea is made of lots of different chemicals. The main ones are polyphenol (includes flavonoids, tannic acid etc) which help the Camellia Sinensis plant fight against predators and ultraviolet radiation. But the polyphenols also benefit in taste, aroma and health through antioxidants. Polyphenols help with digestion, weight management, diabetes, brain function and many other conditions. This is because the antioxidants neutralise harmful free radicals. These free radicals are oxygen containing molecules (ie organic molecules) with an uneven number of electrons, meaning they react easily with other molecules. They can accumulate to cause cell damage and over long periods of time can lead to oxidative stress. 

Photo Credit: Scientific Animations

For these antioxidants to be expressed through tea, scientists say that you should brew tea for 5-8 minutes. I was sceptical about this because I usually take the teabag out after 30 seconds. But I did try it, and it tasted so much better. I usually add spices so my tea to give it some flavour (as I have Indian heritage, I make Indian tea quite often which contains fennel seeds, cardamons, cinnamon, ginger etc) but when I brewed it for 5 minutes, there was so much more flavour and I didn’t need as many spices. I definitely recommend doing this. 

Authentic Indian Cha (tea)

Traditionally, tea was made in a porcelain teapot with expensive china teacups, but few could afford such luxury so people started using cheaper materials. When you make tea in a porcelain teacup you should put the milk first and then the tea from the teapot. The Royal Society of Chemistry says that adding milk to hot tea will affect the taste. This is because the proteins added to the milk will denature (die) because they are heated to a high temperature.  

Photo Credit: Online Galleries. This is an antique porcelain teapot.

When I heard that I was shocked because I always put the milk last. But I discovered that this rule only applies when using a teapot. 

Most people just use a mug and a teabag nowadays, like I do. The rule changes for a mug. You must add the milk after the hot water. If you add the milk before, the cold milk will cool down the water before it has the chance to draw out flavour from the teabag. At a hotter temperature, more flavour is taken out of the teabag. So in this case, you add the milk last. 

To make your tea taste better, you can use a mug or cup that is red in colour. Our brains associate certain colours with tastes. A red cup rather than a white one will trick your brain into thinking your tea is sweet. This is psychological trick that you can try on family members who like sugar in their tea!

The majority of tea drinkers drink black tea or ‘English Breakfast’ tea. When making black tea you use boiling water. But when making green tea, you use cooler water (maybe around 75 degrees Celsius). This is so the green tea doesn’t become too bitter. The science behind this lies in chemistry. Although black and green tea come from the same plant, they are processed differently. After the leaves are picked from the plant, the process of oxidation occurs naturally with the help of the enzyme polyphenol oxidase. Black tea leaves are crushed into fine pieces so the chemicals inside them are exposed, allowing the air to fully oxidise the leaves, converting the polyphenol into theaflavins and thearubigins. On the other hand, green tea is withered (dried to reduce the water content) and heated to prevent oxidation. The heat prevents the activity of the polyphenol oxidase. Therefore, green tea is not as oxidised as black tea. As Thearubigins are the chemicals responsible for the staining property of black tea, the colour of green tea is yellowish green as opposed to reddish brown in black tea. 

Photo Credit: Pouring Tea

An annoying thing always happened to my tea; there would always be a layer of ‘scum’ on the top. This layer is due to the type of water you use. I live in an area where I receive hard water through the tap. Soft water prevents the top layer building up and makes your tea look and taste much lighter. Hard water is basically when rainwater picks up minerals like calcium and magnesium. The calcium hydroxide present in hard water reacts with the flavonoids in tea to produce that layer. Hard water also causes limescale on kettles and increases the amount of rust, which in the long term can damage to pipe systems. 

Researching this was probably one of the most entertaining posts for me because I now know how to make the perfect cup of tea. Although brewing a teabag for 5-8 minutes requires a lot of patience, (a trait I don’t pretend to have) the benefits make it worth it.

If you read this far… you are probably a fellow tea lover!!

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