Corn bran arabinoxylans: Structure-function relationships, gel formation and potential application of the gels as bioactive delivery matrices

Madhuvanti Sharad Kale, Purdue University

Abstract

Colonic diseases such as colorectal cancer and inflammatory bowel disease are major public health concerns in the United States and all over the world. Reduced consumption of dietary fiber is considered to be one of the leading factors associated with these diseases. There is an urgent need to provide preventive as well as therapeutic solutions for these problems. Recently, arabinoxylans, which are cell-wall polysaccharides commonly found in cereal grains, have been the subject of considerable attention due to their good technological and physiological functionality. Previous studies in our laboratory have shown that arabinoxylans extracted from corn bran offer desirable colonic fermentation profiles and can be incorporated at high amounts into extruded foods. The first of this series of studies investigates the relationship between structural and rheological properties of corn bran arabinoxylans, from the perspective of understanding structural determinants of the rheological properties required for fiber incorporation in food. Alkaline extraction is commonly used to isolate arabinoxylans from corn bran. These polymers possess the ability to form covalently crosslinked gels, a property which has not been investigated in depth to date. The gel forming capacity and properties of corn bran arabinoxylan gels such as strength, stability, and crosslinking type and density are reported here, with a detailed study on the effect of the extraction conditions on the gelling properties. Mechanistic insights into the alkaline extraction process, including the kinetics of the extraction process, have been obtained through this study. Arabinoxylan gels have potential applications as matrices for the delivery of drugs and nutraceuticals into the colon. To this end, it is important that the drugs or nutraceuticals should be soluble in the water entrapped in the gels. Previous studies on Sephadex gels, which are covalently crosslinked dextran gels of small pore sizes, have indicated that water in the pores of these gels is capable of dissolving higher amounts of hydrophobic compounds than bulk water. This phenomenon, if applicable to gel systems other than Sephadex, would be of great advantage to the use of gels as bioactive delivery vehicles, since many of the bioactive compounds tend to be hydrophobic in nature. A study on the solubility of a model hydrophobic compound in the internal water of corn bran arabinoxylan gels is reported here. The solubility of this compound was found to be significantly greater in the internal water of the gels, as compared to bulk water. This finding implies that these gels may potentially be used to deliver hydrophobic drugs and nutraceuticals in solution state to the colon, thus providing a simple vehicle for the efficient delivery of these compounds. Thus, corn bran arabinoxylans have the potential to be a part of the solution to the public health problem of colonic disease. Their incorporation at high levels in commonly consumed foods can help with prevention, and the application of their gels as colonic bioactive delivery matrices can be of value in the treatment of the diseases.

Degree

Ph.D.

Advisors

Campanella, Purdue University.

Subject Area

Food Science

COinS