The Organic Flavour Components of Tea

A Sweet Solution

Sugar (sucrose, C₁₂H₂₂O₁₁) is a very popular additive, and understanding how it interacts with water and other molecules is important when considering how it influences the flavours of food and drinks. Research at York has shown that sugar has an important effect in reducing the bitterness of tea and coffee, not just by masking it but by affecting its fundamental chemistry.

Caffeine (C₈H₁₀N₄O₂), as well as acting as a stimulant, is partly responsible for the bitter taste in tea and coffee. In water, caffeine molecules tend to stick to each other, and this is further enhanced by the addition of sugar. As sugar causes the caffeine molecules to clump together, it takes away the bitterness of tea and coffee – as they clump together there is less surface area to arouse our tastebuds and so we find it harder to taste them.

For the first time, work at York suggests that the underlying cause of the clumping is the affinity between sugar molecules and water, which in turn makes the caffeine molecules stick together (or aggregate) in order to avoid the sugar. This work will help food scientists in their development of new tastes.

Sugar-Tax?

In the UK, a levy on sugar-sweetened drinks has been introduced to combat child obesity. It was argued the NHS could save billions of pounds and also thousands of lives in a generation by weaning the public off its sweet tooth.

Today, research has shown that children and teenagers are consuming three times the recommended level of sugar. But, some people object to being taxed for something that causes no harm if eaten in moderation and they don’t want the ‘nanny state’ interfering in their choices.

What do you think?

The Aspartame Controversy

Instead of using sugar to sweeten tea, many people use artificial sweetener aspartame (C₁₄H₁₈N₂O₅). The use of this sweetener has attracted controversy, with claims that it is linked to health problems, including cancer. However, following numerous scientific studies (it is one of the most rigorously tested food ingredients), aspartame hasn’t been linked conclusively to any specific health problems, other than for people with phenylketonuria (a rare genetic disorder in which the body can’t break down the amino acid phenylalanine (C₉H₁₁NO₂), which is produced when aspartame is broken down in the body). Although there are no substantive doubts over the toxicity of aspartame, there is an ongoing debate about the possible influences of non-caloric sweeteners on body weight, and so scientific studies continue.

Those of you who are interested in practical aspects, and who would like to know how to separate a mixture using High Performance Liquid Chromatography (HPLC) (as mentioned in the video above), might like to see this video, made to help prepare our undergraduates before their practicals.