French scientists have reported the successful development of an artificial mouth that chews apples like humans.
Researchers led by Gaelle Arvisenet at ENITIAA in Nantes, France, have designed an artificial mouth that mimics the first vital steps of human digestion i.e. chewing, saliva release and the initial breakdown of food.
The team says that the development could form part of a robotic taste-tester designed to improve food quality and our understanding of flavour.
Earlier groups have developed artificial mouths that can study soft foods or sets of robotic jaws to test teeth. However, until now, none has been able to recreate what happens when a human chows down on hard foodstuffs.
In the study, Arvisenet and colleagues point out that a number of factors are involved in the release of aromatic and flavour compounds in the mouth.
Chewing, the release of saliva, the rate of food breakdown and the temperature all affect the flavour and smell of food before it's swallowed.
To accurately mimic the effects of chewing, Arvisenet's team needed to build a machine that could imitate several of these subtle processes.
"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," New Scientist magazine quoted Arvisenet, as saying.
The munching device reproduces 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 37šC 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.
The researchers compared apples chewed by their machine and by human mouths. The resulting apple pulp was scrutinized for texture, colour and aromatic compound release.
"The [results] were very close," Arvisenet said.