The Compendium of Bheḷa 3.3.12

3.3.12

madhuro ' mlaḥ kaṭuś caivapaktimārgāstrayaḥ smṛtāḥ | kaṭur bhavati pakvasya pacyamānasya cetarau ||

Sweet, sour, and pungent: these are remembered as the three stages of digestion. / Pungent is of the digested [state], and the other two are of that which is undergoing digestion.