At its most basic, a bakery shortening consists of low-melting-point liquid oils and higher-melting-point solid fats that form a soft, plastic material.
“Shortening is a matter of plasticity,” explained Dilip Nakhasi, director of innovation, Bunge Oils, Bradley, IL. “While shortening is a generic term, it relates to smoothness, spreadability and lubricity as well as crystalline structure.”
The solid fats — triacylglycerols, better known as triglycerides — form a crystalline matrix that holds the liquid oils within it, giving the characteristic creamy texture. In baked foods, shortenings impart softness to the crumb structure, provide lubricity to doughs, aid in aeration, stabilize batters and creams by emulsification, improve overall palatability of finished products and extend keeping quality.
Unlike frying oils commonly derived from a single type of oilseed and reflecting that source’s characteristics, shortenings are compound products that can contain many types of fats or processed fat components and, thus, do not reflect a single type of fat.