Do you toast your bagels? This episode explains why some purists call that a crime, starting with the physical science behind a true bagel: low-hydration dough, long cold fermentation, an alkaline boil that forms a gelatinized crust, and a hole that solves a baking problem.

We trace the bagel’s roots from a 10th century Arabic recipe and the Polish obwarzanek to a 1610 Krakow record, then follow it to New York’s Bagel Bakers Local 338, the 1958 bagel machine, the rise of the steamed bagel, and today’s regional debates.

• Why bagel dough sits at roughly 50 to 57 percent hydration and rests cold for at least 12 hours
• How boiling gelatinizes starches to create a crust that keeps the interior dense and chewy
• The bagel’s possible ancestors, from kaak to obwarzanek, and the first written mention in 1610
• How Daniel Thompson’s machine and the Lender family’s frozen, pre-sliced bagels transformed the industry
• New York versus Montreal styles, St. Louis vertical slicing, the flagel, and the slang of bageling