Here is the list of tastes and their combination.
Madhura rasa (sweet) = Prithvi ( earth element) + Ambu (water element)
Amla rasa (Sour) = Agni (Fire Element) + Prithvi ( Earth Element)
Lavana rasa (Salt) = Ambu (Water element) + Agni (Fire Element)
Tikta rasa (Bitter) =Akasha (space element ) + Vayu (air element)
Katu rasa (ungent or spicy) = Agni (Fire element) + Anila (Air element)
Kashaya rasa (Astringent) = Prithvi (earth element) + Anila (air element)