ConAgra Foods, (NYSE: CAG), one of the world's largest branded food companies, and Sigma Alimentos (Sigma), a leading Mexican refrigerated and frozen food marketer, announced yesterday creation of a frozen foods joint venture. ConAgra Foods is acquiring 50 percent of Sigma's frozen prepared foods subsidiary, Sigma Alimentos Congelados, S.A. de C.V., as part of the joint venture. Sigma retains ownership of the other 50 percent. Terms of the transaction were not disclosed.