Butter as a Shortener

When we combine butter and flour, the butter shortens the strands of gluten that make some flour-based preparations chewy, such as bread, resulting in a tender crumb, which you want in a pastry crust or in shortbread. The reason to choose butter as opposed to another fat, such as lard or vegetable shortening or even olive oil (a fat that’s fluid at room temperature), is flavor. The flavor of butter is a natural partner for flour. Try the shortbread for a vivid expression of this.

Remember that butter is composed of 15 percent water, which encourages the formation of gluten, especially with a lot of kneading. Gluten is desirable in a bread or a noodle, but not in a pie crust. Butter will thus have less shortening power than the same weight of a pure fat, such as lard.