Srimad Bhagavatam Canto 11, Chapter 18, Text 05

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.
Srimad Bhagavatam Canto 11, Chapter 18, Text 04
Srimad Bhagavatam Canto 11, Chapter 18, Text 06