During digestion, food is broken down into small particles and mixed with saliva in the mouth before proceeding to the esophagus (food pipe). This process of chewing lubricates the food before it is further mixed with various enzymes and hydrochloric acid within the stomach. From here it proceeds to the small intestines.
http://www.newtimes.co.rw/section/article/2016-07-18/201795/
Why acid reflux could spell more trouble