LOS ANGELES (MarketWatch) -- Taco Bell restaurant-chain founder Glen Bell Jr. passed away Sunday at the age of 86, according to Yum Brands Inc.'s YUM, +0.65% Taco Bell Corp. Bell's first venture in the restaurant business was in 1948, when he opened Bell's Drive-In, in San Bernardino, Calif., originally serving hamburgers and hot dogs, but later moving to differentiate the menu by adding Mexican fare. "Once he perfected his taco shell recipe, taco sauces and the convenient drive-thru concept he was ready to introduce the tastes and textures of Mexican food to mainstream America," the Taco Bell statement said. Taco Bell now serves more than 36.8 million consumers each week in more than 5,600 restaurants in the U.S., the company said.