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December 16, 2013

Embedding molecules in starch may help prevent Type 2 diabetes

Srinivas Janaswamy

Srinivas Janaswamy 
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WEST LAFAYETTE, Ind. - A Purdue University researcher has developed a novel method of modifying the digestion of starch, potentially offering a simple, cost-effective way of preventing Type 2 diabetes.

Srinivas Janaswamy, research assistant professor of food science, found that inserting "guest" molecules into the natural structure of potato starch causes glucose to be released more slowly during in vitro digestion. Slow, sustained glucose release could help stave off Type 2 diabetes and other health problems associated with elevated blood glucose levels.

"Embedding molecules in the water pockets of starch is a simple and practical way of tweaking starch digestion," Janaswamy said. "Having the ability to slow down the digestion of starch would revolutionize the way we approach a number of health issues."

Starch is a vital and inexpensive source of energy for humans and is digested at varying speeds, depending on the food product. Rapidly digestible starch is absorbed quickly by the body, leading to a faster accumulation of glucose in the blood, one of the conditions that can cause Type 2 diabetes, a chronic ailment that affects the way the body metabolizes glucose.

Janaswamy discovered that embedding "guest" molecules in raw potato starch significantly altered starch digestion rates, in some cases slowing the release of glucose by 22 percent during the initial 120 minutes of in vitro digestion.

"We will now be in a position to tailor treatments to patients by developing starch products with customized glucose release rates," he said.

Developing food products with controlled starch digestion would be a positive step in preventing Type 2 diabetes at minimal cost, he said.

Further, adding beneficial "guest" molecules such as vitamins, drugs, dietary supplements and flavor compounds to starch could promote health, prevent disease and improve food flavor. In his study, Janaswamy successfully embedded a variety of molecules, including vitamin C, ibuprofen, curcumin and the flavor compound thymol.

"We could use this research to create food products that deliver healthful compounds to the body - potato chips that contain extra vitamins or antioxidants, for example," he said.

Guest molecules could also provide a means of delivering targeted medicines to the colon, the site of fermentation for certain kinds of starches.

Janaswamy embedded guest molecules in the natural structure of potato starch, which has a latticelike arrangement of water channels and starch double helices. He dissolved the guest molecules in a solvent and added them to submerged raw potato starch granules. The guest molecules then became entrapped in the water channels of the starch.

"We're not chemically modifying starch in any way," he said. "We're taking advantage of its native structural arrangement at the molecular level to alter digestion rates."

Because humans cannot digest raw starch, further research is needed to ensure that cooking the starch does not destroy the guest molecules, said Janaswamy.

"I believe that even if the starch is cooked, we will be able to preserve the functionality of the encapsulated molecules," he said. "This could be a completely new way to add health-promoting compounds to food products."

The paper is available in Carbohydrate Polymers at http://www.sciencedirect.com/science/article/pii/S0144861713009958 

The Whistler Center for Carbohydrate Research provided funding for the research.

Writer: Natalie van Hoose, 765-496-2050, nvanhoos@purdue.edu

Source: Srinivas Janaswamy, 765-494-4914, janaswam@purdue.edu

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ABSTRACT

Encapsulation altered starch digestion: Toward developing starch-based delivery systems

Srinivas Janaswamy

Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, USA

E-mail: janaswam@purdue.edu 

Starch is an abundant biomaterial that forms a vital energy source for humans. Altering its digestion, e.g. increasing the proportions of slowly digestible starch (SDS) and resistant starch (RS), would revolutionize starch utility in addressing a number of health issues related to glucose absorption, glycemic index and colon health. The research reported in this article is based on my hypothesis that water channels present in the B-type starch crystalline matrix, particularly in tuber starches, can embed guest molecules such as nutraceuticals, drugs, flavor compounds and vitamins leading to altered starch digestion. Toward this goal, potato starch has been chosen as the model tuber starch, and ibuprofen, benzocaine, sulfapyridine, curcumin, thymol and ascorbic acid as model guest molecules, X-ray powder diffraction and FT-IR analyses clearly suggest the incorporation of guests molecules in the water channels of potato starch. Furthermore, the in vitro digestion profiles of complexes are intriguing with major variations occurring after 60 min of starch digestion and finally at 120 min. These changes are concomitantly reflected in the SDS and RS amounts, with about 24% decrease in SDS for benzocaine complex and 6% increase in RS for ibuprofen complex, attesting the ability of guest molecule encapsulation in modulating the digestion properties of potato starch. Overall, this research provides an elegant opportunity for the design and development of novel starch-based stable carriers that not only bestow tailored glucose release rates but could also transport health promoting and disease preventing compounds.


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