Why candies with salt are sweeter

  There is such an experience in life: Sprinkling a little salt on sweets can increase the sweetness. For example, salted caramel is sprinkled with sea salt on top of the caramel. It has a salty taste in the mouth, but it is quickly replaced by the sweetness of caramel. A recent study published in the “Acta Physiology” provides scientific evidence that salt can increase sweetness.
  People’s ability to taste food comes from the receptor cells of the taste buds of the tongue. The sweetness is detected by the T1R receptor family, which can sense natural sugar and artificial sweeteners at the same time. But in 2003, researchers discovered that mice or humans have another way to perceive sweetness.
  To find the answer, the team of Keiko Yasumatsu, a physiologist at Tokyo Dental College in Japan, studied a protein that works with glucose: sodium-glucose cotransporter 1 (SGLT1). In the kidneys and intestines, SGLT1 uses sodium to carry glucose into cells and provide energy for the cells. Strangely, this protein is also present in taste cells that are sensitive to sweet taste.
  The researchers wiped the tongues of unconscious T1R mice with a glucose-salt solution (which contains the sodium required for SGLT1) and recorded the neural responses connected to taste cells. They found that salt seemed to play a big role: it caused a more rapid neurological reaction in mice compared to mutant mice given only glucose, and conscious mice also seemed to prefer sugar-salt solutions. But this reaction only applies to glucose, sweeteners such as saccharin will not cause this reaction.
  In addition, compounds known to inhibit SGLT1 also prevented mice from responding to glucose, indicating that SGLT1 may be a hidden glucose sensing pathway. Although this pathway helps knockout mice to sense glucose, in normal mice, it may enhance the sweetness captured by the T1R receptor. Yasumatsu believes that this discovery may even be applicable to humans and could explain the popularity of foods such as salted caramel.
  The researchers also summarized three kinds of taste cells that are sensitive to sweet taste. The first two use the T1R and SGLT1 pathways separately to help the body distinguish between natural sugars and artificial sweeteners. The third is the mixed pathway of T1R and SGLT1, and it responds to fatty acids and umami. Researchers believe that this provides a way to detect high-calorie foods.