Sadrasa - six flavors

Everything that is a manifested material has what Ayurveda calls flavors. Everything that is manifested is the outcome of a process of production, and each such process involves ingredients, a manufacturer and a method. The flavors are a result of that process. The kind of material that is produced can be described through its flavors, which reveal something about the basic ingredients. There are six of them. 

Each of the flavors enumerated in the list in the verse is more powerful or forceful than the next (sweet is greater than sour, which is greater than salty, which is greater than pungent, which is greater than astringent, which is greater than bitter). Sweet is also heaviest, bitter is lightest. If we think of the ripening of fruit, for example, unripe fruit is bitter and ripened fruit is sweet.

The direct cause of the living body, what perpetuates it, is food. The ras, which is the first dhatu, conveys the guny, which derive from the mahabhutas. Every material also has its own dharma. The dharma of sugar, for example, is to be sweet - it will never be otherwise. The dharma of any material is to achieve the highest good, the most perfect expression. 

Svadu is usually translated as "sweet", but a better translation would be "beneficial" or "delicious", and the sense of it is something that is 100 % acceptable for use as an ingredient in a process. This does not mean it will be beneficial, people often find "delicious" things that are not eventually beneficial to them, but that is because these processes involve multiple factors. 

The dharma of food is to contribute to the growth and maintenance of the body. It comes into the body through the mouth and the tongue is the first sensory organ it encounters. The tongue has several different kinds of cells on its surface, called papillae, which communicate the flavor to the nervous system. The best way for the flavors to be experienced is in a fluid form, and that is why our digestive system involves adding saliva to whatever is ingested to transform it into the fluid that will become ras, the first dhatu. Different dishes that we eat involve the combination of the flavors, and sometimes we can taste and distinguish their individual ingredients.

In this verse, Bagbhat enumerates the six flavors, like Charaka and Susruta do in their compilations. In Ayurveda, flavors derive from the Mahabhutas, the basic elements. Two schools explain the origin of the flavors differently. One considers the origin of flavors to be from the element of Water (Jala), the other believes they all dervie from the element of Earth (Pritvi).

In both schools, the sweet flavor is considered to be the elements of Earth and Water combined, but the salty and sour flavors are differently explained. According to one, the salty flavor is Fire and Earth and the sour flavor is the Fire and Water. According to the other, school it is vice versa: the salty flavor is Fire and Water and the sour taste is Fire and Earth.

All schools agree that the pungent flavor is connected to the element of Fire, the astringent flavor is the element of Air and Earth and the bitter flavor is Ether and Air.

The sweet flavor is considered to be the heaviest and the bitter flavor the lightest. We can imagine the lightness and heaviness of tastes according to the Mahabhutas. In one school the order from heavy to light is: sweet, salty, sour, pungent, astringent and bitter, in the other the order is: sweet, sour, salty, pungent, astringent and bitter.