Organic acids can be produced naturally by plants and animals. If they have one or more carboxyl group, they are called carboxylic acids and are found in for example stinging nettles and red ants. By mixing acids and alcohols you can produce esters. Esters are substances with strong aroma and taste properties and they are often used as flavourings in food. This film is all about the chemistry of organic acids and esters. For example, you will learn that corboxylic acids containing longer carbon chains are called fatty acids, and that they can be either saturated, unsaturated or polyunsaturated.