In the great heirarchy of bagel quality, New York City seems to reign suppreme. But why, exactly, the Big Apple reigns supreme is a matter of debate, as narrator Noel Waghorn states in the American Chemical Society's latest explainer video above. For years, some New York residents have been touting city water, as the primary source of their bagel success. And it's true, the water does make a difference. But it's not the only thing that influences the taste, Waghorn says.
New York's water, which flows from the Catskill Mountains, is particularly soft and has low levels of calcium and magnesium. Ratios of these minerals in water affect the gluten in the bagel dough. Hard water fortifies gluten, the protein responsible for toughness in bagels. Using super soft water, on the other hand, turns dough to goo. New York's water is a bit like the Goldilocks of bagel water chemistry: just the right softness, creating just the right degree of tenderness and chewiness in the resulting bagels.
This also means that for those beyond the city's reach, all is not lost. Even if you don't have New York City's water, you could recreate it, as the video notes, by tweaking the chemistry of the dough or filtering your water source.
But the tap water is just one factor in a myriad that influence bagel quality. Setting the dough aside and letting it sit in a refrigerator also coaxes yeast to ferment, releasing volatile flavor compounds. Before the oven, boiling the bagels in a bath of water (and baking soda) locks water molecules into the dough's starch. This boiling step is called poaching and creates the crunchy exterior and chewy inside of a classic bagel. NYC's bagel shops routinely practice both of these bagel prep methods, while some other regions don't — so it's not just the water that makes the bagel.