Do you remember the amazing refreshing feeling of a glass of lemonade on a hot summer's day? You may have noticed the sharp sour taste of the lemonade. This tartness is a result of carboxylic acids. This is an organic acid that is found in a variety of fruits including grapes, lemons and vinegar.
What is a carboxylic acid?
Carboxylic acid is a form of organic acid. You can identify these acids by their structure. They all contain one carbon atom, one oxygen atom and one hydroxyl group. The combination of one carbon, one oxygen and hydroxyl group (COOH )is called a carboxyl group. It is because of this that acids derived from them are called carboxylic acids.
The combination of one carbon, one oxygen and hydroxyl group (COOH )is called a carboxyl group.
Where do you find carboxylic acids?
Carboxylic acids are widely found in nature. You can find them as free acids like citric acid, tannic acid and malic acid. Esters – the products of acids and alcohols also contain carboxylic acids. These include fats and oils, flavours of fruits and odours of flowers. Some bacteria can also cause natural reactions in which these acids are formed. Some examples include acetic acid from wine or cider, lactic acid found in sour milk and the butyric acid in rancid butter.
Types of carboxylic acids
This acid is found in vinegar and is responsible for giving it the sour taste. Vinegar means sour wine. It was discovered when bacteria reacted with wine and turned it sour. It is one of the simplest of carboxylic acids.
You may have heard of this acid, it has been used for tanning. You will find it in the bark of a number of trees. Tannic acid can be found as a yellow or light brown powder, which is highly soluble in water. It is used for the staining of wood and is also used when dyeing cotton.
This acid is derived from the bark of the willow tree. Salicylic acid is used in acne creams to help reduce acne. It derives its name from the word Salix, which is Latin for Willow. Today this acid is used as a food preservative.
This acid is found in most citrus fruits. It gives the tangy taste to lemons, limes, grape fruits and oranges. Citric acid is a natural preservative and used in both foods and soft drinks. It is also used in some bathroom and kitchen cleaning solutions.
This acid is found in many unripe fruits like green apples. Malic acid includes green apples, plums, currants (seedless raisins) and a variety of other fruits.
This acid was originally derived from the wood sorrel plant Oxalis. It is now made artificially and is used in bleaching and cleansing solutions.