Monosodium glutamate (MSG) is a common food additive. It is the sodium salt of the amino acid glutamic acid. It is used to flavour foods with the taste of umami, the savoury fifth flavour that is associated with being a ‘pleasant-savoury’ flavour.
The flavour umami is conferred by free L-glutamate and commonly found in mushrooms, meat and soy sauce. MSG is freely soluble in water due to its salt nature. The ionic bond (shown in red) breaks to form two hydrophilic ions upon dissolving.