Production of baked goods that are light-textured yet contain a healthy dose of fiber is a major focus of the commercial baking industry, which is embracing a homely sounding ingredient called resistant starch to get the job done. Resistant starch, which occurs naturally in fresh foods and is processed into powder for baking, is also touted as a weight-loss aid that helps burn fat. It is beginning to find its way into home baking pantries.
Carboyhydrates, such as grains, were once defined as containing digestible starches and indigestible fiber. But in recent decades, researchers have divided the composition of carbohydrates into three categories: fiber; starches, such as sugar, that the small upper intestine can digest; and starches, such as high-amylose corn starch, that resist digestion in the small intestine and act like fiber.
Resistant starch and fiber don't increase calories or blood sugar. They travel on to the lower intestine where they help regulate colon health. "Baking Management" magazine says that unlike regular fiber, resistant starch ferments in the large intestine. This fermentation helps create a feeling of satiety that aids weight loss. "Baking Management" notes that the fermentation may also help control diabetes by improving the body's insulin sensitivity -- the ability to respond to and metabolize glucose.
Amylose vs. Amylopectin
The digestible portion of starch contains amylopectin, which is soluble in water. Resistant starch is high in amylose, which is mostly insoluble in water. Sticky rice is an example of a starchy food that contains almost no amylose, according to the Food Republic website. When cooked in hot water, sticky rice becomes gluey due to its high amylopectin content. While some researchers are seeking to decrease the costs of producing digestible starches by developing potatoes high in amylopectin, others are focusing on creating resistant starch from potatoes high in amylose.
Resistant Starch Sources
Commercial bakers are particularly interested in high-amylose modified starches to meet consumer demand for products that taste good but decrease calories and increase fiber. Interest is also growing among home bakers, especially those limited to low-fiber, gluten-free flours and powdered starches. The most efficient resistant starch product on the market at present is high-amylose cornstarch made from corn with starch containing 50 percent or more amylose.
So far, few retail grocers carry high-amylose cornstarch for home bakers, but a product called Hi-maize can be purchased online. Other good sources of resistant starch easily available to home bakers include alternative gluten-free flours -- such as ones made from beans and Ethiopian teff grain -- as well as slightly green bananas and russet potatoes.
High-amylose cornstarch can be substituted for up to 25 percent of standard wheat flour in a recipe without harming texture or flavor, according to the website FoodProcessing.com. The website quotes a King Arthur Flour representative as saying that one "beauty" of high-amylose cornstarch is that it's "nearly invisible" in baked goods. Bakers who prefer a whole grain earthiness to their baked goods may prefer to obtain resistant starch from heavier textured and tasting bean flours or slightly nutty and somewhat gritty teff. The Bob's Red Mill website says teff can be substituted for 25 percent of the all-purpose flour in recipes.