Acid
We generally refer the word acid for those parts that through their union with oxygen get a bitter flavour. They have the property to dye by red colour many blue vegetable colours, as the litmus dyeing and the colour of violets. They strongly involve other bodies and create salts with alkalis, the earths and metals. In Grappa the most representative one is the acetic; then it follows the formic, butyric, lactic, propionic, isovalerian and so on. They organoleptically refer to the classical flavour perceptible on the tongue edges. The acids combined with the alcohols give rise to esters that have got a great importance during the organoleptic characterization of Grappa.
