Gum arabic
Due to the oily nature of these active substances (essential oils, tinctures and extracts), pastilles are usually based on mixtures of starch and gum arabic, which emulsifies the substance and binds them in a hydrocolloidal matrix. The starch and gum also reduces the rate in which the pastille dissolves and moderates the amount of active substances delivered at a time. Gum arabic also hardens the pastilles and makes them more sturdy in storage and transport.