The quest for optimal nutrition is constantly discovering new uses for traditional nutrients. Even something as stodgy sounding as starch gets its fifteen minutes of fame. Resistant starches, which are sometimes found in bread, are currently of interest due to their low glycemic response, which makes them potentially useful in the management of blood sugar disorders.
Resistant Starches
Resistant starches are starches that do not digest completely in your small intestine. These undigested starches then pass into your colon, where the beneficial bacteria that reside there digest it -- a process called fermentation. Resistant starches are contained in the cell walls of plants, where human digestive enzymes cannot access them. Processes such as cooling and reheating certain foods can also create resistant starches. Not all forms of bread contain resistant starches. Flours made from refined grains lose their resistant starch, but whole-wheat flour retains it.
Types
There are four general types of resistant starch, according to Pei Tze Ang of the University of Nebraska. Resistant starch type 1, or RS1, is heat stable, which makes it useful as an ingredient in breadmaking. RS2 is made from raw potatoes and green bananas. High-amylose maize starch is another type of RS2 and it maintains its digestive resistance even when cooked. Cooling gelatinized starch creates RS3. It is the type of starch most resistant to digestion and is widely used as a food ingredient. A chemical process that modifies the digestibility of the starch produces RS4.
Sources
Resistant starches are derived from a number of ingredients that can be used in bread. Corn, wheat and other legumes, nuts and grains are sources of resistant starch. Whole-wheat flour is a natural source of resistant starch that is commonly used in bread. High-amylose cornstarch, marketed as "hi-maize" fiber, is a whole grain corn flour that can be used in baking applications. It is sold by natural foods retailers.
Bread Ingredients
According to the journal "Nutrition Research," the use of resistant starch as a bread ingredient may help reduce glucose absorption and lower the bread's glycemic index. The study found that rats fed resistant starch wheat bread ate less, had lower total cholesterol and lower blood glucose levels after eating. Additionally, rats fed with resistant starch maize bread had less weight gain and lower total cholesterol levels, but no change in postmeal blood glucose levels.
References
- University of Nebraska-Lincoln; Adaptation and Validation of Existing Analytical Methods for Monitoring Prebiotics Present in Different Types of Processed Food Matrices; Pei Tze Ang; 2011
- Linus Pauling Institute at Oregon State University; Fiber; Jane Higdon; December 2005
- "Nutrition Research"; Maize and Resistant Starch Enriched Breads Reduce Postprandial Glycemic Responses in Rats; C.M. Brites; April 2011
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