How Sugar Changes the Chemistry of Tea

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The caffeine in your cup may boost your day but is also leaves a slightly bitter taste in your mouth.

blue sugar spoonBitterness is more pronounced not only in greater concentrations but also when caffeine molecules are more widely dispersed in the tea. Chemists at the York Structural Biology Laboratory at the University of York, England, recently discovered how sugar reduces bitterness by forcing caffeine molecules into clusters.

Dr. Seishi Shimizu, in a research paper published in the journal of Food and Function, observed that caffeine molecules aggregate in order to avoid sugar. It is the affinity between sugar molecules and water that corrals the caffeine making it less accessible to taste buds in the mouth.

It was previously thought that sugar masked the bitterness experienced by receptors in the mouth. Shimizu’s work shows the underlying cause was not the strengthening of bonds between water molecules around the sugar. “Proper understanding of the fundamental rationale behind this process may assist food scientists in many ways,” according to the university.

sugar spoonShimizu demonstrated the effect without spilling a crystal through the use of statistical thermodynamics, “a branch of theoretical physical chemistry linking the microscopic realm with the everyday world,” reports

“It is delightful indeed that food and drink questions can be solved using theory, with equipment no more complex than a pen and paper. Encouraged by this discovery, and our recent success on how to make jelly firmer, we are working hard to reveal more about the molecular basis of food and cooking,” said Shimizu.

Source: University of York,, Food and Function

‘Caffeine dimerization: effects of sugar, salts, and water structure’ published in the July edition of Food and Function