Why Does The Facial Expression Grimacing When Eating Sour Food? Turns Out This Is The Reason

Illustration of facial expression grimacing while eating sour food (Unsplash/Diana Polekhina)

YOGYAKARTA - Young mango, star fruit, or sour orange create a tingling sensation and naturally make the face express a grimace. The sensation of sour taste, was not limited to the tongue alone.

Quoted from Mental Floss, the sour taste that pierces the tongue is the result of the work of hydrogen ions released by acid when it combines with saliva. Taste receptors are activated after receiving dramatic information from the acid. Your face will grimace involuntarily in what is known as the rejection response.

Your tongue's reaction to bitter or spicy food is also a response to rejection. Many plants found in nature with this taste are toxic, and your body's strong reaction is its way of protecting you from harm. Sour tastes occur naturally in fruits like oranges, but in many cases can be a warning sign of foodborne illness. Rotting fruit and dairy products contain acid, which gives them a sour taste too.

It's hard to ignore the sour taste of what you eat when it changes your entire facial expression. This reaction is not necessarily enough to help someone who has bitten a bad apple, but it can protect those who are with them. When ancient human ancestors searched for food, facial expressions were often a reference for sorting and choosing foods that were not good to eat.

The shriveled response to sour taste helped early humans avoid getting sick, but that doesn't stop us from eating acidic foods today. The taste is so sought after that there is an entire candy market devoted to maximizing it in processed products. So why do we like to eat something that is warned by our face and tongue that it can kill us?

The answer is an acquired taste. Humans do not naturally crave bitter, spicy, or sour foods, but foods with these characteristics are an important component of a nutritious diet. Instead of loving this taste from birth, we are conditioned to enjoy it through repeated exposure. By recognizing taste through our peers and family members, humans gradually learn which acidic (and bitter and spicy) foods are healthy and which are potentially harmful.