If you’re interested cooking up antojitos at home, don’t start with masa harina, the corn flour you mix up with water. Drive a few miles out of your way to buy freshly ground masa. “There’s a major difference — the aroma, the texture, the corn taste,” says Manuel Berber, the owner of Mi Rancho Tortilla Factory in San Leandro. “Corn flour is a sandier-tasting product and it’s real dense. There’s no texture to it.”
To make masa, field corn is cooked with lime before being ground. According to Berber, that’s because the lime helps the kernels soften and absorb water. But the lime also solves a tricky little nutritional problem. Corn is deficient in two amino acids, lysine and tryptophan. More critically, all of its niacin, a B vitamin, is locked inside and completely non-bioavailable. Niacin deficiencies are responsible for pellagra — a disease that plagued polenta-dependent rural Italy and the grits-and-cornmeal-dependent rural American South for centuries. Yet all the peoples of Central and South America are pellagra-free. Back around 1000 BC, according to the archaeological evidence, some culinary genius in coastal Guatemala figured out that cooking the corn with lime or wood ash causes the grain to release its niacin.
At La Mexicana in Hayward, one of a few midsize, family- owned tortilla factories in the East Bay, Jesus Villarreal oversees the operation his uncle started in 1965. His crew starts work at 10 p.m., cooking dried white corn (white number-one fancy, to be exact) in large vats of a solution of water and powdered lime. Once the corn is cooked, the workers let it steep for 24 hours, filling the industrial room with a comforting smell halfway between roasted corn and polenta. On their next shift, they grind it in a deceptively small mill with two granite millstones at its core. Seventy-five percent of the masa goes into the tortilla-making machine. The rest — some two thousand pounds — is bagged in five- and ten-pound plastic bags, to be sold in La Mexicana’s store and shipped around the South Bay.
Half of La Mexicana’s bagged masa is finely ground, for use in tortillas and other antojitos. The other half is ground coarse, mixed with lard, and sold for tamale making.
La Mexicana’s tortillas and fine-ground masa have only three ingredients: corn, lime, and water. “If you see a pure white tortilla,” Villarreal says, “it has citric acids and preservatives. It will also have a slightly acidic smell.”
Buy masa the day you’re going to use it, because it only keeps in the fridge for two days, and doesn’t freeze well. Villarreal says you’ll be able to tell when the masa goes bad because white spots will form on the surface of the dough and it will start smelling acidic. You can find fresh masa at a number of Mexican markets around the East Bay. But if you want it from the source, here are two local factories: La Mexicana, 236 A Street, Hayward, 510-889-8225; and La Finca, 3809 Foothill Blvd., Oakland, 510-536-1200.