Concentration and shear rate dependence of solution viscosity for arabinoxylans from different sources

Authors: KALE, MADHUVANTI - Z-Trim Holdings, Inc; Yadav, Madhav; Hicks, Kevin; HANAH, KYLE - Z-Trim Holdings, Inc

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2015
Publication Date: 1/26/2015
Publication URL: http://handle.nal.usda.gov/10113/61076
Citation: Kale, M.S., Yadav, M.P., Hicks, K.B., Hanah, K. 2015. Concentration and shear rate dependence of solution viscosity for arabinoxylans from different sources. Food Hydrocolloids Journal. 47:178-183.

Interpretive Summary: Plant cell walls are rich in carbohydrate polymers, called Arabinoxylans (AXs). Arabinoxylans are not digestible by humans, and act as dietary fiber that has very important health benefits. In order to include more Arabinoxylans in the human diet, it is essential to know the flow behavior of these polymers so that they can be incorporated into foods. Arabinoxylans also have many potential industrial applications, for which their flow behavior needs to be known. It is known that structure of polymers affects their flow behavior, but it is not clear whether small differences in structure significantly affect flow behavior. In this study, we compared the flow behavior of Arabinoxylans from seven different sources. We found that, in spite of some differences in the structure of the seven polymers, they showed some similarity in terms of their flow behavior. The properties shown by all polymers suggest that there are clear relationships between aspects of structure and flow behavior, and that there are some unique properties of Arabinoxylans as a class of polymers. These findings will help further utilization of these polymers, which are very abundantly available from low-value agricultural by-products, in food and non-food applications. Thus these results may benefit farmers because utilization of these products will ultimately improve the markets for agricultural by-products. It will also benefit the U.S. consumers, food and non-food industries and ultimately the U. S. economy.

Technical Abstract: Arabinoxylans are cell wall polysaccharides abundant in plants. Alkaline extraction is commonly used to isolate arabinoxylans from cell wall rich materials, such as cereal brans, crop residues etc. While arabinoxylans from certain sources such as wheat endosperm, corn bran and rye bran have been widely studied, there is a lack of studies focusing on the rheological and molecular properties of arabinoxylans from a wide variety of different sources. In this study, we report the concentration and shear rate dependence of solution viscosity of alkali extractable arabinoxylans from seven different sources. All the polymers are found to show Newtonian flow behavior, particularly at low concentrations, which is considered unusual for high molecular weight polysaccharides. The concentration dependence data shows the presence of a single critical concentration, suggestive of random coil conformation, while the rate of viscosity change in the two regimes suggests a more rigid conformation. This seemingly contradictory behavior is explained on the basis of a semi-flexible conformation of arabinoxylans in solution, which has been reported previously. The critical concentration of the arabinoxylans showed a strong correlation with their molecular weight, thus suggesting that fine structural differences do not significantly affect this aspect of rheological behavior. This is the first comparative study of alkali soluble arabinoxylans from different sources, and suggests that this class of polymers has significant similarities in spite of heterogeneity of fine structure.