Some varieties of resistant starch are made from wheat and can help fortify bread products.

Resistant Starch

Also known as Enzyme-resistant Starch


What is Resistant Starch?

Resistant starch (RS) is one type of dietary fiber. It’s defined as the total amount of starch and the products of starch degradation that resist digestion in the small intestine of healthy people.1 In baking, it’s used to improve the nutritional value of baked goods by reducing starch digestibility.

Sources examples are:

  • Wheat starch
  • Oats
  • Raw potato starch
  • Legumes
  • Green bananas
  • High-maize flour
  • Retrograded starches

Origin

The term “resistant starch” was first introduced by Englyst et al. in 1982 to describe a small fraction of starch that is resistant to hydrolysis by exhaustive alpha-amylase and pullulanase activity in vitro.2

Four types of resistant starch are known:

  • RS1: starch trapped in non-starch polysaccharides
  • RS2: crystalline starch in grains, raw potatoes and green bananas
  • RS3: retrograded starch
  • RS4: chemically- and enzymatically-modified starch

Nutrition and health

Many health benefits are associated with eating resistant starch. By escaping digestion in the small intestine, fermentation of RS in the large intestine produces organic short chain fatty acids (SCFA), which have been shown to be beneficial to colonic health. RS provides important biological effects such as:3

  • Improved glycemic index
  • Controlled insulin responses
  • Gut health
  • Reduced blood glucose spikes after a meal
  • Production of beneficial short chain fatty acids (SCFA) in the colon

Commercial production

RS1 and RS2 are present in unprocessed and uncooked foods, but RS3 and RS4 can be prepared by selection of appropriate ingredients. Grains with high amylose content are suitable for the preparation of RS3. Here, as the long amylose chains cool down, they adopt a coil structure of retrograded starch which is resistant to enzymatic attack.

Types

The scientific community and regulatory agencies currently recognize 4 forms of RS:1,4

RS1
RS1 is the type of starch that is physically inaccessible to pancreatic amylolytic enzymes and protected to the action of stomach hydrochloric acid due to entrapment by intact cell wall tissues (e.g. cellulose, hemicellulose and lignin). Examples include whole or partially milled cereal grains, coarsely ground seeds and legume kernels.

RS2
It comprises native starch granules protected from digestion by the impervious and highly crystalline structure of the starch granule. RS2 includes native starch, such as high-amylose maize or raw banana starch.

RS3
RS3 encompasses the retrograded starch formed when starch-containing food is cooked then...


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