Multiple choice The substance that lubricates the food in the alimentary canal is hydrochloric acid ptylan mucin pepsin Reveal answer Fill a bubble to check yourself C Correct answer Explanation Mucin is the mucus secretion that lubricates food in the alimentary canal, helping it move smoothly. Hydrochloric acid digests food, ptyalin (salivary amylase) digests starch, and pepsin digests proteins.