Preheat the oven to 350°. Lightly grease 4 timbale molds or 4-ounce custard cups. In a medium-size heavy saucepan, combine the water, cornmeal, cumin, chili powder and salt. Bring to a boil, stirring occasionally, over moderate heat. Lower the heat, cover, and cook stirring occasionally, for 8 to 10 minutes or until very thick. Remove from heat.
In bowl, beat egg whites until foamy. Whisk about a quarter of hot cornmeal into beaten whites, then slowly pour the whites into the remaining cornmeal mixture, stirring constantly, about 1 minute more or just until thickened.
Divide the mixture among the prepared molds, pressing the surfaces with the back of a spoon. Cover loosely with aluminum foil. Place the molds in an 8"x8"x2" baking dish filled halfway with hot water. Bake for 20 to 25 minutes or until heated through. Let stand for a few minutes to set. Run a small spatula or knife around the sides of each mold and invert carefully onto serving plates. Serve 4.