Foods like oranges, lemons, yogurt and apples have a sharp taste because they contain naturally occurring acids. Citrus fruits contain citric acid, apples contain malic acid and yogurts are rich in lactic acid. In this text-based activity, students summarise the functions and uses of citric acid as a food additive.

Fats
Many foods contain fats and unsaturated fats are prone to oxidation. If this happens, they can produce unpleasant and harmful substances which make the food