“After the churning, O Brahmana, had gone on for some time, gummy exudations of various trees and herbs vested with the properties of amrita mingled with the waters of the Ocean. And the celestials attained to immortality by drinking of the water mixed with those gums and with the liquid extract of gold. By degrees, the milky water of the agitated deep turned into clarified butter by virtue of those gums and juices. But nectar did not appear even then.

In plain words: As the churning continued, healing saps from trees and herbs mixed into the ocean, and the gods became immortal by drinking that water. The milky sea slowly turned into ghee, or clarified butter. But the real nectar still had not appeared.