( Grains ( ( begin ( digesting ( in ( ( the mouth ) ( with ( saliva ( while chewing ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Grains)) (VP (VBP begin) (S (VP (VBG digesting) (PP (IN in) (NP (NP (DT the) (NN mouth)) (PP (IN with) (NP (JJ saliva) (NN while) (VBG chewing)))))))) (. .)))
Grains begin digesting in the mouth with saliva while chewing.
(ROOT (S (NP (NNP Saliva) (NNP secretion)) (VP (VBZ initiates) (NP (NN chemical) (NN digestion)) (PP (IN while) (S (ADVP (RB also)) (VP (VBG protecting) (NP (DT the) (JJ oral) (NN cavity)))))) (. .)))