Brahmanas states that the members of three varnas or classes have three different objectives to be achieved namely the brahmanas holy luster or brahma varcas, the Kshatriyas physical strength or viryas and the vaisyas cattle wealth or pasavah. They have, therefore, prescribed those food articles, which might enable the bramanas to acquire maximum of holy lustre, Kshatriyas maximum of physical strength and the vaisyas maximum of cattle wealth. As is clearly stated in the Bhagavad-Gita, the society was divided into four varnas on the basis of inherent qualities of the individuals namely, sattva or purity and goodness, rajas which makes a man luxurious and tamas i.e. darkness or ignorance and their duties as members of these three varnas.
As per Baudhayana, brahmanas should be feasted with apupas dhanah or parched grain, odana or boiled rice, saktus or groats at the upakarman ceremony i.e. inaugural ceremony of an academic session. The Aitareya Brahmana mentions shoots of banyan tree and fruits of fig, plaksa or ficus infectoria and asvattha or ficus religiosa trees as fit food for ksatriyas. This recommendation seems to have been made in view that the Kshatriyas might not get cooked food while going on a campaign of conquest. From the Apastamba Srauta Sutra, it can be known that boiled rice or groats prepared in melted butter or ajamantha was the food of the brahmanas, those prepared in milk or payomantha that of the Kshatriyas, those prepared in curds or dadhimantha that of a vaisya and those prepared in water or udamantha that of the sudras.
The above description clearly shows that the dishes were prepared according to the objectives to be attained by the members of different varnas. According to the Aitareya Brahmana, soma is the food for brahmanas, curds for vaisyas and water for sudras. From the Kathaka samhita, it is known that drinking sura or liquor by brahmanas was considered a sin but not so in the case of Kshatriyas. The Satapatha Brahmana contrasts soma and sura by saying soma is truth, prosperity and light and sura is untruth, misery and darkness.
From the above explanation, it is clear that brahmanas did not drink liquor because they were expected to set an example to the members of the other three varnas of the society. On the other hand, the ksatriyas could drink sura even on solemn occasions like the coronation ceremony. Sura was the common drink of the ksatriyas as is clear from a reference in the Aitareya Brahmana where it is stated that the priest placed a vessel of sura in the hands of the king after the coronation ceremony.