That taste should count as a fundamental principle of reality, on equal footing with sight or hearing, is a specifically Samkhya commitment worth pausing on, since most philosophical systems that enumerate basic categories of existence do not give the sense of taste its own dedicated slot at all. Rasana, the tongue's underlying faculty, is exactly as fundamental in this scheme as chakshu or shrotra: each of the five Jnanendriyas is one of twenty-five tattvas, no more and no less basic than the others, and rasana's single tanmatra, rasa, is treated as a real feature of the material world rather than as a merely subjective sensation layered onto it afterward.
Rasa, the tanmatra rasana perceives, sits fourth among the five in most orderings, denser than shabda, sparsha and rupa, subtler only than gandha, smell. This position places rasana's corresponding gross element, apas, water, near the bottom of the elemental sequence, and Indian cosmological writing generally credits water with carrying flavour distinctively, food and drink dissolved in or mixed with water being where taste is most readily experienced, a correspondence the tattva chain states as a structural fact rather than as observation alone.
Because rasana, like the other Jnanendriyas, is produced from the sattvic aspect of ahamkara, it shares their purely receptive character: it registers rasa, contributes that registration to manas for synthesis with the other senses, and does nothing further. The active complement to eating and tasting, in this scheme, belongs elsewhere, to payu and to the Karmendriyas generally, keeping Samkhya's strict division between perceiving and acting intact even in a function as physically involved as eating.