Aspartame is an artificial sweetener sold in the market. It consists of amino acids and provides calories like other amino acids. Yet, it is used as a low-calorie sweetening agent in food items. What is the basis of this use?

The correct answer is D. Aspartame is a dipeptide of aspartic acid and phenylalanine, and it is roughly 180 to 200 times sweeter than sucrose. So a very small quantity gives the same sweetness as a large amount of sugar, and the calories it adds to the food are correspondingly tiny. The calorie value per gram is not zero, but the amount used is negligible.

• A is wrong. The body does metabolise aspartame, breaking it into aspartic acid, phenylalanine and methanol. Its low calorie use comes from potency, not from enzyme deficiency.
• B is wrong. Aspartame is actually heat-unstable and breaks down in cooking and baking, which is why it is used mainly in cold or low-heat products.
• C is wrong. The metabolites, especially amino acids and methanol, do yield some energy. The claim of zero-calorie metabolites is false.

The concept here is intense sweetness and dose-based calorie reduction. For Mains, it links to food labelling, FSSAI regulations on permitted sweeteners, and the WHO/JECFA acceptable daily intake of 40 mg per kg body weight. Note that products containing aspartame must carry a warning for people with phenylketonuria.

Trap: Aspirants assume that an artificial sweetener must be non-metabolised or calorie-free. The point is that it is metabolised and does carry calories, but the potency is so high that the quantity needed is minimal.