 They found that the must from Pedro Ximénez (PX) grape oxidized more slowly and added its own dimension of strength and sweetness to wine that it was blended with.Wines with significant proportions of PX added started to be called "Cream" or "Sweet" Sherry.Throughout the course of the 19th century, Sherry competed with Rioja for the distinction of being Spain's most recognizable wine and would be considered by many wine critics as one of the great expressions of white wine in the world.