The data in Fish is adapted from Cornell (1990) and comes from an experiment to optimize the texture of fish patties. The columns Mullet, Sheepshead, and Croaker represent what proportion of the patty came from those fish types. The column Temperature represents the oven temperature used to bake the patties. The column Rating is the response and is a measure of texture acceptability, where higher is better. A response surface model was fit to the data and the prediction formula was stored in the column Predicted Rating. (For more information, see Mixture Profiler in the Profilers book.)
Select Help > Sample Data Library and open Fish
From the Graph menu, select Ternary Plot.
Select Mullet, Sheepshead, and Croaker and click X, Plotting.
Select Predicted Rating and click Contour Formula.
From the red triangle menu, select Contour Fill > Fill Above.
Ternary Plot with a Contour Formula

Help created on 9/19/2017