Now, an artificial mouth ‘that can chew like a human’

But, until now, no one has been able to recreate what happens when a human chows down on hard foodstuffs.

“Many of the flavours we taste are generated by the release of volatile compounds from food, which pass around the back of the mouth and up into the nose. Hard foods release those compounds differently according to whether they are crushed, sliced, or liquidised.

“So if a robotic system is going to experience the same tastes that humans do when eating, the food must undergo the same changes that occur in the mouth.

“Previous models were simpler and did not take into account all processes involved in perception of food. Our artificial mouth allows the study of hard foods like apples,” said lead researcher Galle Arvisenet of ENITIAA in France.

In fact, the munching device mimics the first steps of digestion — chewing, saliva release and food breakdown.

About five times the size of a human mouth inside, the steel container is kept at a steady 37C by an electrical element. Its internal surfaces are coated with a chemically resistant plastic used for medical implants.

The ceiling and floor of the cylindrical chamber are attached to variable speed motors. Food is placed on the floor which is able to revolve, while the ceiling coated spiky “teeth” moves up and down like a plunger.

The compression and rotation simulate the mechanical forces food undergoes in the mouth. The process is made more realistic by the addition of enzyme-containing artificial saliva through a pipe in the base of the chamber.

Helium supplied through another inlet flows through the “mouth” to reproduce the effect of breathing and carry volatile compounds away for analysis.

To hone their robotic mouth’s chewing action, the researchers fed it chunks of apple and set it chewing at different speeds. They then compared the final pulp with apple chewed by humans.

“The (results) were very close,” Arvisenet wrote in the ‘Journal of Agricultural and Food Chemistry’.