In Ayurveda, ahara (food), swapna (sleep) and brahmacharya (celibacy) are considered as tryo-upasthambhas or sub-supporting pillars of life. Food is critical for the sustenance of life; it is the first of the three, followed by sleep and brahmacharya. Foods are any substances containing nutrients, such as carbohydrate, proteins and fats that can be ingested by a living organism and metabolized into energy and bodily tissues. Digestion is the process of breakdown of complex form of food into simplest monomers through enzymatic process in gastrointestinal tract. In Ayurveda, conversion of hetrogenous panchbhautic ahara (complex food) into its basic homogenous panchmahabhuta (simplest monomers) is directed by the synchronization of three sets of agni; jathragni, dhatwagni and bhutagni. The process of digestion, metabolism and assimilation is mainly accomplished by agni. The site of jathragni is grahani or pakvamashaya better known as pittadhara kala. Samana vayu, Pachaka pitta and kledaka kapha helps in digestion. Samana vayu which is present near the vicinity of agni stimulate the pachakagni for the digestion and separation of food. Kledaka kapha is present in the stomach which softens the food materials. Ayurvedic classics explains the whole process of digestion that starts with the intake of food, takes place in three stages called as Avastha paka, these are Madhur avastha paka, Amla avastha paka and katu avastha paka. Few works have been mentioned on conceptual features of avastha paka in relation to modern physiology. In this article correlation of the physiological concept of avastha paka with modern medical science has been stated. For this study, the basic materials have been collected from the Ayurvedic classics with the available commentaries, as well as Text books of modern medical science better understanding of the concept and its comparison with contemporary science.