SB 11.18.5
agni-pakvam samasniyat
kala-pakvam athapi va
ulukhalasma-kutto va
dantolukhala eva va
Translation:
One may eat foodstuffs prepared with fire, such as grains, or fruits ripened by time. One may grind one’s food with mortar and stone or with one’s own teeth.
Purport:
In Vedic civilization it is recommended that at the end of one’s life one should go to a holy place or forest for spiritual perfection. In sacred forests one does not find restaurants, supermarkets, fast-food chains and so on, and thus one must eat simply, reducing sense gratification.
Although in the Western countries people eat processed food, one living simply must himself separate and pulverize grains and other foods before eating. This is referred to here.