SB 3.26.42

kaṣāyo madhuras tiktaḥ
 kaṭv amla iti naikadhā
bhautikānāṁ vikāreṇa
 rasa eko vibhidyate
Word for word: 
kaṣāyaḥ — astringent; madhuraḥ — sweet; tiktaḥ — bitter; kaṭu — pungent; amlaḥ — sour; iti — thus; na-ekadhā — manifoldly; bhautikānām — of other substances; vikāreṇa — by transformation; rasaḥ — the subtle element taste; ekaḥ — originally one; vibhidyate — is divided.
Translation: 
Although originally one, taste becomes manifold as astringent, sweet, bitter, pungent, sour and salty due to contact with other substances.