Definition of 'optimum'. optimum (ÉptÉªmÉm ) or optimal. The optimum or optimal level or state of something is the best level or state that it could achieve. Aim to do some physical activity three times a week for optimum health. ...regions in which optimal conditions for farming can be created.
Use Tapioca Flour. Also know as tapioca starch, it's a great substitute. You'll want to use 2 tablespoons for every 1 tablespoon of cornstarch. Use Rice Flour. Rice flour thickens up like regular flour so use the same proportion: 3 tablespoons for every 1 tablespoon of cornstarch.
Corn flour and corn starch are the same thing. In the United States the starch is known as corn starch, but in most commonwealth countries and in the EU, it is known as corn flour. Source(s): http://en.wikipedia.org/wiki/Cornstarch.