THURSDAY, Nov. 25 (HealthDay News) -- U.S. scientists say they've made a surprising discovery on just how acidic foods make us pucker up.

First, some background: Acidic substances such as lemons and pickles evoke the sour sensation. The more acidic the substance, the more sour the taste.

Acids release particles at the atomic level called protons. The neurobiology researchers at the University of Southern California expected to find that protons from acids bind to the outside of the cell and open a pore in the membrane that enables sodium to enter the cell. The entry of sodium would send an electrical response to the brain to announce a sour sensation.

Instead, the team found that the protons released by acids enter the cell and directly trigger the electrical response.

The findings, published Nov. 23 in the journal Proceedings of the National Academy of Sciences, may have practical applications for cooks and the food industry, said senior author Emily Liman, an associate professor of neurobiology.

"We're at the early stages of identifying the molecules that contribute to sour taste," she said in a USC news release. "Once we've understood the nature of the molecules that sense sour, we can start thinking about how they might be modified and how that might change the way things taste. We may also find that the number or function of these molecules changes during the course of development or during aging."

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