Polenta and masa harina are both types of ground corn that can be prepared into versatile doughs. The corn used to make masa harina is nixtamalized; that is, cooked for hours and mixed with an alkaline ingredient such as ash or limestone. This process that has been used for hundreds, if not thousands of years in the Americas. It changes the flavor (deeper, more complex), makes the nutrients more available and also increases its viscosity. has a deeper, more complex flavor.