Diet cola is described as ‘diet’ as it is essentially sugar-free. To put things in context, a 350-millilitre (0.7-pint) can of regular cola contains approximately 37 grams (1.3 ounces) of sugars, which is around 40 per cent of the recommended daily intake of sugar for adults. In contrast, the same-sized can of diet cola contains no sugar and, as a result, only delivers 1.5 calories to the consumer.
Diet cola, without sugars for sweetening, must instead rely on an artificial non-saccharide (that is, carbohydrate-free) sweetener called aspartame to maintain its flavour. Aspartame is a methyl ester of the dipeptide (a molecule consisting of two amino acids) of the natural amino acids L-phenylalanine and L-aspartic, both of which are synthesised for its production. Unlike sugars, aspartame can hydrolyse, or break down, under high temperatures so it can’t be used in hot beverages or for baking.
Once synthesised, aspartame is around 200 times sweeter than sucrose, and also delivers a longer-lasting flavour. As such, only incredibly small quantities of aspartame are included in each can of diet cola (roughly 180 milligrams/0.006 ounces), which is over 205 times less material compared to the sugars that are used in a can of the non-diet version of this popular pop.