Eating slowly makes food taste better

Feeling hungry can cause us to eat more quickly, but it turns out that your mum’s advice to slow down was right all along — eating slowly will actually make food taste better.

US researchers wanted to better understand how the process of tasting food works. Tasting relies on food volatiles moving from the back of the mouth to the nasal cavity, but researchers have wondered why airflow doesn’t carry them in the other direction, into the lungs.

With the help of a 3D-printed model of the human airway from nostril to trachea, a team of engineers was able to study the movement of air into and out of the airway. They determined that the shape of the airway preferentially transfers volatiles to the nasal cavity and allows humans to enjoy the smell of good food.

“During quiet breathing, there is no valve that can control the direction of volatile transport,” said Rui Ni, assistant professor of mechanical engineering, Penn State. “However, something must be controlling the movement of these particles and keeping them out of the lungs.”

Physiologists have previously looked at the nasal passages, but not at the pathway from the back of the mouth to the nose. Using data from CT scans, and the help of two radiologists, the team built a schematic of the human airway from the nostrils to the trachea, including the fine structure. They then used the schematic to make a model using a 3D printer.

They found that chewed food particles end up in the back of the mouth in a sort of side cavity to the main airflow. When air is inhaled through the nose, the airflow forms an air curtain to prevent volatile particles released from the back of the mouth from escaping into the lungs. However, when air is exhaled, it sweeps into the area with abundant food volatiles, moving them into the nasal cavity where they are sensed by olfactory cells.

Movement of the particles is also affected by the speed of breathing. Slow, steady breathing optimises the unsymmetrical transport effect and allows more air to sweep particles out and up.

“Smooth, relatively slow breathing maximises delivery of the particles to the nose,” said Ni. “Food smells and tastes better if you take your time.”

The results were reported in a recent issue of Proceedings of the National Academy of Sciences.