Saliva changes how food tastes

Ever wondered why some people love certain foods like red wine while others hate it? New research suggests taste preferences are influenced by proteins found in saliva, and when people were repeatedly exposed to bitter foods their saliva adapted to make it more palatable.

Saliva has a number of roles, including breaking down food and lubricating the throat, but it also contains proteins that are part of a feedback loop influencing how food tastes. Researchers said this impacts a person’s eating habits, and hope their findings could help consumers train themselves to enjoy a healthier diet.

Healthy foods such as broccoli and dark chocolate are nutritious but they can also taste bitter, causing many consumers to opt for sweeter options. Cordelia Running from Purdue University investigated whether eating more bitter foods would help people get over this aversion. She said, “By changing your diet, you might be able to change your flavour experience of foods that at one point tasted nasty to you.”

Salivary proteins can bind to flavour compounds in food and to taste receptor cells in the mouth, and certain proteins may be responsible for the unpleasant, bitter or rough tastes.

“If we can change the expression of these proteins, maybe we can make the ‘bad’ flavours like bitterness and astringency weaker,” said Running, Principal Investigator.

Participants were asked to rate the bitterness and astringency of chocolate almond milk three times a day for a week. The researchers found a change in the participants’ saliva protein composition over the course of the week. After drinking the chocolate almond milk, there was an increase in proline-rich proteins, which can bind the bitter/astringent compounds in chocolate, while participant’s sensory ratings for bitterness and astringency decreased. Running said they believe the body adapts to reduce the negative sensation of these bitter compounds.

The findings support the idea that saliva influences flavour and, therefore, a person’s dietary choices. “Those choices then influence exposure to flavours, which over time may stimulate altered expression of saliva proteins, and the circle begins anew. Maybe this knowledge will help someone stick to a healthier diet long enough to adapt to like it,” she said.

Running plans to investigate the specific compounds that cause changes in salivary proteins. She also wants to evaluate the time it takes to reduce the bitter taste and whether mimics for salivary proteins could be added to food to improve its flavour.

The results were presented at the 256th National Meeting & Exposition of the American Chemical Society.

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