The Collaborative International Dictionary of English v.0.48:

Mastication \Mas`ti*ca"tion\, n. [L. masticatio: cf. F.
   mastication.]
   The act or operation of masticating; chewing, as of food.
   [1913 Webster]

         Mastication is a necessary preparation of solid
         aliment, without which there can be no good digestion.
                                                  --Arbuthnot.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mastication
    n 1: biting and grinding food in your mouth so it becomes soft
         enough to swallow [syn: chew, chewing, mastication,
         manduction]