Chocolate chip cookies are an iconic American food. They are consistently rated America’s favorite cookies, year after year. But there’s a surprising secret ingredient that keeps chocolate chip cookies fresh: nitrogen.

Chocolate chip cookies were invented in the 1930s by Ruth Wakefield, who owned a restaurant called Toll House in Whitman, Massachusetts. The recipe was an instant success, and by World War II chocolate cookies were an important addition to care packages sent to American soldiers overseas. A Nestlé ad even encouraged women to use their chocolate rations to bake cookies for “that soldier boy of yours.”

Today, Americans eat an estimated 7 billion chocolate chip cookies each year. About half of that number––3.5 billion––comes in the form of store-bought cookies. But chocolate chip cookies, full of gooey chocolate, rich butter, and tasty dough, have an enemy: mold.

Mold is a fungus that grows on food, and eating moldy food can be a serious health hazard. Sadly, the delicious ingredients in chocolate chip cookies make them a perfect breeding ground for mold. For years, cookies had a short shelf life because of mold formation.

Then came Modified Atmosphere Packaging, a technological breakthrough that nowadays helps keep all kinds of foods safe. The process removes air, including oxygen which supports mold growth, from inside packages and replaces it with gas, often nitrogen. Nitrogen is a stable, unreactive gas. Inerting chocolate chip cookie packages with nitrogen inhibits the growth of mold and the cookies stay fresh longer., and it

Nitrogen protects 3.5 billion cookies each year from mold, not to mention a host of other foods, and it can also be used to protect your tires. Oxygen is bad for tires, just like it’s bad for cookies. It contributes to oxidation which can cause the rubber to become brittle and weak, and form rust on metal wheel components. Inertion––the process of removing regular air, including water vapor, and replacing it with nitrogen––protects tires just like it protects chocolate chip cookies.

So, the next time you enjoy a delicious chocolate chip cookie, remember you can keep your tires fresh, too, with nitrogen inertion.