Examining the nutraceutical properties of starches

August 9, 2017

Starch digestibility has been associated with the glycemic index (GI) to assess the nutritional quality of foods. An article published in the Journal of Food Science explores the structure and nutraceutical properties of resistant starch and slowly digestible starch. Twenty-five years ago, it was found that a significant fraction of the starch present in foods is not digested in the small intestine and continues to the large intestine, where it is fermented by the microbiota; this fraction was named resistant starch (RS). It was also reported that there is a fraction of starch that is slowly digested, sustaining a release of glucose in the small intestine. Later, health benefits were found to be associated with the consumption of this fraction, called slowly digestible starch (SDS).

Currently, consumers and the food industry are interested in foods with low postprandial glycemic response and high indigestible carbohydrate content. Therefore, SDS and RS have been widely studied due to the findings that they have beneficial health effects. SDS is slowly digested throughout the small intestine, resulting in a slow and prolonged release of glucose into the bloodstream, which is coupled to a low glycemic response.

The nutraceutical importance of RS is attributed to the fermentation of RS, since it resists digestion in small intestine; instead, it reaches the large intestine, where it can act as a substrate for the selective growth of prebiotic bacteria such as lactobacilli, bifidobacterial, and streptococci, which are known to be beneficial and might enhance human health.

The authors declared both fractions to be “nutraceutical starch.” Developing methods to produce RS and SDS using isolated starch and processes to produce starchy foods with increased levels of both RS and SDS fractions is a challenge for researchers and industry. The authors stated that the strategies for RS and SDS production should utilize information about the structure that causes the resistance or slow digestion of starches by digestive enzymes. In this sense, it will be possible to produce tailor-made nutraceutical starch. The authors concluded that the “current challenge for the food industry is to develop new technologies or methods to obtain heat-stable SDS/RS structures that resist changes that may occur during food preparation.”