What chemical test can detect the presence of starch?

The Iodine test is used to detect the presence of starch.

The Iodine test is a simple and effective method for identifying the presence of starch in a substance. It is based on the reaction between iodine and starch to produce a blue-black colour. This test is commonly used in laboratories and classrooms to demonstrate the principle of complex formation between iodine and starch.

To perform the test, a small amount of the substance to be tested is mixed with a few drops of iodine solution. If starch is present, the mixture will immediately turn a deep blue-black colour. This is due to the formation of a starch-iodine complex, which is intensely coloured. The intensity of the colour is directly proportional to the amount of starch present, allowing for a rough estimation of the starch content.

The iodine test is not specific to starch, as it can also give a positive result with other polysaccharides. However, the blue-black colour produced with starch is distinctive and easily recognisable. It's important to note that the test will not work if the starch is in a very concentrated solution or if it has been broken down into its component sugars, as the iodine can only react with the intact starch molecule.

In conclusion, the iodine test is a quick and easy way to detect the presence of starch. It is a valuable tool in both educational and research settings, providing a visual demonstration of the interaction between iodine and starch.