Taste is one of the attributes of food. According to ayurvedic text books and principles of ayurveda, tastes are of six types. We all know there are 5 fundamental elements or panchamahabhutas. Each taste has combination of two fundamental elements. The combination of fundamental elements determines the qualities of respective taste or rasa.
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)