This classic nag for children is actually un-true.
The stomach has acid and an enzyme called pepsin which begins the process of digestion before the contents are propelled towards the small bowel or intestine where the process continues for absorption to begin. In fact the only products that can be absorbed by the stomach wall include water, alcohol and aspirin. This explains their rapid effects when thirsty with a drink of water, the feeling of relaxation after an alcoholic drink or the rapidity of the cure of a headache after taking 2 aspirins.
John Farrell conducted an experiment at Bristol Dental Hospital over 30 years ago where he arranged for his students to swallow muslin bags with food to be swallowed without chewing. After 30 minutes the muslin bags were retrieved with attached lines and the contents inspected.
All the contents were completely digested, irrespective of the size of the particles of food, proving scientifically that chewing was an irrevelance to digest food. However chewing does stimulate gastric/stomach secretion of acid and prevents choking. Every one has had the opportunity to observe a dog bolting it’s food with no chewing. In fact, the dog is incapable of chewing due to the design and arrangement of it’s teeth that only allow for tearing and ripping off flesh from bones.
Social courtesies dictate that we chew in public to conform. Obsessives will often promote the need for chewing (Nancy Regan) a minimum of times before swallowing but these are to be regarded as purely a manifestation of her own personal neuroses and insecurities associated with anorexia.
Chewing does not contribute one iota towards digestion, but choking to death in front of fellow diners is considered bad manners…